The young football team trapped underground in Thailand are still too weak to attempt to leave their flooded cave with two boys and their coach suffering from exhaustion, it has emerged.

Rescuers are beginning to pump oxygen into the chamber in Chiang Rai, northern Thailand, where the 12 boys and their coach have been trapped for 12 days.

A medical assessment has found that it is still too dangerous to try to move the youngsters, an unnamed source in the Thai Navy Seals told CNN.

Two boys and the 25-year-old coach are suffering with exhaustion through malnutrition, according to a new doctor's report.

It comes with rescuers facing a race against the weather to save the 12 children as it emerged volunteers accidentally pumped water back into the caves.

Heavy rainfall is expected in the coming days and attempts are being made to lower flooding levels - but this has been hampered after unregistered volunteers started pumping water back into the caves in the belief they were helping.

Young footballers (pictured) trapped in caves in Thailand were forced to go deeper into the mountain after the original ledge they were on became submerged in rising flood water, it has emerged

Water was accidentally pumped back into caves by volunteers amid desperate attempts to lower flooding levels in the sprawling underground network, it has emerged

Today, a team of bird's nest collectors from southern Thailand arrived to put their generations-old rock climbing skills to use to help with the rescue mission.

The eight men are Thai Muslims from Libong island in Trang province, where they climb limestone cliffs to collect the edible nests, a delicacy made from solidified bird spit that can go for hundreds of pounds per kilo.

'One member in our team was watching (the rescue mission) on television and thought 'how can we help them?',' team leader Abdulrawheep Khunraksa said.

'We thought that we might have the expertise to help since we have climbed to collect bird's nests for generations,' the 49-year-old added.

Armed with ropes, gloves and their knowledge, the team set off up the steep slope in the hopes of finding an alternative route to reach the boys inside the Tham Laung cave.

News of the 600ft move into the mountain comes as authorities warned rescuers were in a 'race against water' to evacuate the boys before expected heavy rainfall

The 12 youngsters and their coach had to abandon the 'Pattaya Beach' area of the caves in Chiang Rai on Monday night and are now perched on a bumpy ledge known as 'Women's Boobs' where they were found, officials have revealed

Rescue teams hope that water can be sufficiently drained, allowing the trapped children to wade to safety while wearing lifejackets.

A former US Navy SEAL with thousands of hours of experience of diving in difficult conditions has warned that there will be fatalities if the children have to dive out.

Cade Courtley said the situation was currently stable and non life threatening, but that 'some of these kids are going to die' if they are made to swim through the narrow dark tunnels.

It comes after Tham Luang operation commander Narongsak Osotthanakorn said unregistered volunteers had been diverting water back into the ground in the belief they were helping.

'They may have some belief that their technique is effective for ground water drainage, but anything that is not in the plan must be discussed with us first,' he said.

Mr Narongsak, the former Chiang Rai governor, added: 'We are concerned about rain. We are racing against water. Water is flowing into the cave although we have plugged its channels.'

In a further twist, he revealed that a new phone was being transported to the cave after a previous device fell in the water and stopped working.

He also revealed the children have undergone their first day of scuba diving training in preparation for their evacuation.

They will undergo a thorough medical examination to decide whether they are fit enough for the arduous escape.

Governor Narongsak said: 'Pattaya Beach is now covered in water and the boys are now at the ledge that is known as Women's Boobs.'

He added that the boys and their coach were in good spirits and their health was improving following their first meal in days.

Family members pass time near the Tham Luang cave complex, where members of an under-16 soccer team and their coach have been found alive

Chiang Rai provincial governor Narongsak Osatanakorn, who is overseeing the rescue, said 30 teams are searching for an airhole

US Navy SEAL predicts deaths if trapped cave children swim out A former US Navy SEAL has warned of fatalities if the young Thai footballers have to dive their way out of the cave network. Cade Courtley says such an attempt should be the last option for the trapped youngsters - because they have 'time on their hands'. Courtley told CNN he had thousands of hours of experience operating in 'zero visibility' water as part of a special diving unit. He questioned why the idea of diving the boys out was being considered when high powered pumps existed that were capable of draining a thousand gallons of water a minute. He said: 'In my experience I would consider this stable and non life threatening which means we have the luxury of time - and with that time we are able to do a risk anaylsis on all of our options. 'I keep hearing the option of dive them out and I think that should be the very last option.' The former US Navy SEAL added: 'I hate to say this but some of these kids are going to die in an effort to try and bring them out using dive equipment.' Advertisement

Authorities did not under-estimate the challenge facing the youngsters, Governor Narongsak said, revealing that it took the Thai Navy Seals six hours to reach the boys and five hours to return, negotiating their way through the complex cave system.

But he said: 'The water level remains the main concern and the need for urgency.'

It comes as it emerged there may be a secret passage out of the cave. The boys aged 11 to 16 told rescuers they have heard dogs barking, roosters crowing and children playing despite being 800 metres underground.

This has led officials to think there may be another way out through a 'chimney hole' to the surface.

Osatanakorn, who is overseeing the rescue, said 30 teams are searching for an airhole. He believes there must be one for the boys to have been able to breathe for so long.

If rescuers can drill down to the boys, that would offer an alternative to teaching them how to swim and scuba dive so they can be led to safety through the flooded cave.

The 2.5km swim through mud-clogged water would be 'extremely dangerous,' experts say, but the boys have already started diving practice as rescuers race against time to get them out before more monsoon rains cut them off.

The boys aged 11 to 16 told rescuers they have heard dogs barking, roosters crowing and children playing despite being 800 metres underground. Pictured: Police at the scene

Team work: Thai soldiers are pictured carrying equipment as they make preparations for what will be a tense rescue operation

The youngsters aged 11 to 16 and their 25-year-old coach were on Monday found alive by British volunteer divers John Volanthen and Rick Stanton after nine days lost in the Thamg Luang cave network in the country's north, which they reportedly entered as part of an initiation ritual. Pictured: Rescue workers in the cave complex on Wednesday

Australian Federal Police and Defense Force personnel talk each other near a cave where 12 boys and their soccer coach are trapped

On Wednesday Mr Osatanakorn said that 'all 13 may not come out at the same time.'

He said authorities will evaluate their readiness each day and if there is any risk will not proceed.

'If the condition is right and if that person is ready, 100 per cent, he can come out,' he added.

It comes after a new video was released showing the boys in good spirits after 11 days underground.

The boys and their coach are seen sitting with Thai Navy Seals in the dark cave with their visibly skinny faces illuminated by the beam of a flashlight.

The youngsters, many wrapped in foil warming blankets, take turns introducing themselves, folding their hands together in a traditional greeting and saying their names and that they are healthy.

The minute-long video was recorded some time on Tuesday and was posted on the Navy Seal Facebook page on Wednesday morning.

The boys and their 25-year-old coach disappeared after they went exploring in the Tham Luang Nang Non cave in northern Chiang Rai province after a football game on June 23.

The 12 boys and their coach are seen sitting with Thai Navy Seals in the dark cave with their visibly skinny faces illuminated by the beam of a flashlight

Rescue workers are seen by the Tham Luang Nang Non cave in northern Chiang Rai province

Meanwhile, the anguished mothers of the stranded school boys today offered prayers for the swift rescue of their beloved sons.

Nine relatives of the missing footballers lit incense sticks made offering of rice to a shrine just yards from the entrance of the Tham Luang cavern, near Mae Sai, in the far north of the country.

In a moving ceremony the mothers bowed their heads in prayer in front of statue of Buddha and called upon the deity to make the water flooding the cave recede and for their sons to be brought to the surface quickly and safely.

Among the family members was Ratdao Chantapoon, the mother of Prajak Sutham, 14, one of 12 boys from the Wild Boar football team who ventured into the underground network with their coach last month.

A friend revealed that the mothers decided to pray and make offerings to the Buddha and the sacred spirit.

'They want to do everything they can to help their boys and get them home as soon as possible,' she told MailOnline.

'They have faith in the rescue operation to bring them out of the cave safely.

'But they wanted to offer their prayers to the sacred spirit to help.'

The teammates, who were trapped inside when heavy rains flooded the cave, were found by rescue divers late on Monday night.

A desperate search drew experts from around the globe, including British divers Rick Stanton and John Volanthen, who were the first rescuers to reach the group.

Authorities said the boys, who had also been shown on Tuesday in a video shot by the British divers, were being looked after by seven members of the Thai Navy Seals, including medics, who were staying with them inside the cave.

They were mostly in stable condition and have received high-protein drinks.

In both of the videos, the boys have appeared in good spirits.

A desperate search for them drew assistance from experts around the globe

Workers bring supplies for the trapped boys, who were trapped inside when heavy rains flooded the cave

'He was a sad boy': Trapped Thai football coach lost all his family to illness and became a monk Ekkapol Chantawong, 25, is trapped in the cave with his 12 young players. When he was just 12, he lost his seven-year-old brother, mother and father as an illness spread though his home. His aunt said he was a 'sad and lonely' boy until he was sent a to Buddhist monastery where he gained mental strength. He has reportedly been teaching the boys to meditate to help keep them calm in the cave. Ekkapol Chantawong, 25, is trapped in the cave with his 12 young players His aunt said he was a 'sad and lonely' boy until he was sent a Buddhist monastery where he gained mental strength. Pictured: The coach with his players The coach has reportedly been teaching the boys to meditate to help keep them calm in the cave Advertisement

The youngsters were on Monday found alive by British volunteer divers John Volanthen and Rick Stanton after nine days lost in the Thamg Luang cave network in the country's north, which they reportedly entered as part of an initiation ritual.

Officials were facing a stark choice to either keep the terrified boys in the pitch-black cave for up to four months until the water level subsides or teach them how to dive and guide them out through narrow passages and murky waters.

With heavy monsoon rains expected which could cut the boys off from help and supplies, they have taken the 'unbelievably dangerous' option to chaperone them 1.5miles to the cave entrance through water likened to 'cold coffee'.

The 12 teenagers and their 25-year-old coach were found alive by British volunteer divers John Volanthen and Rick Stanton on Monday after nine days lost in the Thamg Luang cave network (pictured) in the country's north

While efforts to pump out floodwaters are continuing, some Thai officials have indicated that heavy rains forecast for this weekend could force them to decide the boys should swim and dive out using the same complicated route of narrow passageways through which their rescuers entered

A Thai army medic slips as his comrades carry a stretcher during a training exercise as rescuers work at the scene in Thailand

Rescuer workers prepare small diving masks to deliver to the youngsters inside Tham Luang Nang Non cave

A Thai navy officer carries a pig's head to worship celestrial guardians and spirits as the rescue operations for the child soccer team and their coach continue

Family members of the 12 boys and their soccer coach watch a video clip of 12 boys on television after they were found alive, in Mae Sai, Chiang Rai province

Thai Interior Minister Anupong Paojinda has said the boys' only chance is to swim out through the flooded underground network and that swimming lessons will start on Wednesday or Thursday.

He said on Wednesday: 'There are no other options besides getting them out through the flooded passages.'

Thai Navy Seal Chief Admiral Aphakorn Yoo-kongkaew has vowed to reunite the 12 boys with their families and said the operation would only begin when the youngsters are mentally ready and physically fit.

Huge pipes have been placed in the tunnel network in the hope of lowering the level of water in the cave network

Authorities said the boys, who had also been shown Tuesday in a video shot by the British diver who discovered them, were being looked after by seven members of the Thai navy SEALs, including medics, who were staying with them inside the cave. They were mostly in stable condition and have received high-protein drinks

Concerned family members are escorted by police close to the Tham Luang cave complex in northern Thailand

He said on Wednesday: 'Anyone who is ready first will be brought out. They will be brought out gradually. Safety is the priority.

'The first plan is to reduce the water level and get them out but if we can't, we will have a backup plan.

'It may be four months, one month or one week. There's no need to hurry.'

Rescuers Wednesday morning carried a rehearsal of evacuating the 12-stranded schoolboys from the flooded Thamg Luang cave.

Soldiers from the Thai Army practiced escorting the youngsters to a make-shift hospital set close to the entrance of the cave.

Volunteers, posing as the 12 stranded footballers, were taken to a triage area for a medical examination.

Thai police and soldiers are pictured as rescue operations continue for 12 boys and their coach trapped at the Tham Luang cave

A family member smiles near the Tham Luang cave complex after new video emerged showing the boys laughing and joking

Thai rescue personnel work to pump water from the Tham Luang cave. Teams have been pumping 10,000 litres of water out of the caves every hour. But this is only enough to lower the level by one centimeter

Thai soldiers carry supplies as they walk down the hill leading up to Tham Luang cave as rescue operations continue for 12 boys and their coach

They were then transported by ambulance down the muddy, mountain track to hospital in Mae Sia, in a simulation of a real emergency plan.

Meanwhile huge volumes of water are being pumped out of the cave network as rescuers frantically try to evacuate the boys before their window of opportunity is closed by the monsoon rains.

The forest clearing by the entrance to the cave has become a media village with dozens of news organisations from across the world anticipating the rescue.

Make-shift kitchens are dishing out hundreds of meals to volunteers, police officers, soldiers and rescue workers.

Rescuers are sent inside Tham Luang Nang Non cave network as rains continue to stream down raising fears the boys will be trapped for a long while

A Thai rescuer prepares oxygen tanks for diving after the 12 boys and their soccer coach were found alive in Mae Sai, Chiang Rai province

Family members watch news about the rescue operation at a makeshift camp at Khun Nam Nang Non Forest Park

On Tuesday, Thai officials said they are waiting for the youngsters to regain their strength before possibly moving them out 'in the coming days.'

Belgian diver Ben Reymenants, the owner of Blue Label Diving in Thailand who is assisting the search, revealed to Sky News that the boys left their backpacks and shoes 'before wading in and trying to go to the end of the tunnel, sort of like an initiation for local young boys to… write your name on the wall and make it back.

'Now a flash flood because of sudden heavy rain locked them in.'

Teams have been pumping 10,000 litres of water out of the caves every hour. But this is only enough to lower the level by one centimeter and more rain is forecast sparking fears it will threaten the air pocket where the team has taken refuge.