Eight schoolboy footballers have been rescued from a flooded Thai cave, with four of their teammates and their coach still trapped inside following the second day of a dramatic rescue operation.

Four boys were freed within three hours of each other on Monday evening, more than a fortnight after the group entered the Tham Luang network of caverns in the country’s northern Chiang Rai province.

Officials said the boys were “safe and conscious” in hospital, where they will be reunited with four of their teammates who were rescued on Sunday.

The boys were guided out of the sprawling and treacherous network of underground tunnels by an international team of divers taking part in a high-stakes rescue operation that has transfixed the world.

“We have helped four more children today,” said rescue chief Narongsak Osottanakorn, after efforts were halted for the night. He said rescuers would resume work in the hope of freeing the remaining five people in about 20 hours’ time.

“The health of the remaining five people inside the cave is still good,” Mr Narongsak added.

Authorities said Prayut Chan-o-cha, the Thai prime minister, would visit all eight boys already rescued in hospital on Monday night in hospital.

The Facebook page of Thailand’s Navy Seals, who have been central to the rescue operation, was updated with a post reading “two days, eight boars” – a reference to the Wild Boars, the name of the boys’ football team.

Authorities have been rushing to free the boys, between 11 and 16, and their 25-year-old coach from the cave as the annual monsoon bears down on the mountainous region.

Chiang Rai governer Narongsak Osatanakorn told a press conference that rescue workers had been able to work quicker on Monday because of their earlier experience of navigating the cave’s treacherous passages.

Thailand schoolboys rescue - in pictures Show all 21 1 /21 Thailand schoolboys rescue - in pictures Thailand schoolboys rescue - in pictures Police and military personnel use umbrellas to cover a stretcher near a helicopter and an ambulance at a military airport in Chiang Rai as rescue operations continue for those still trapped inside the cave in Khun Nam Nang Non Forest Park in the Mae Sai district. Four boys among the group of 13 trapped in a flooded Thai cave for more than a fortnight were rescued on July 8 after surviving a treacherous escape, raising hopes elite divers would also save the others soon. AFP/Getty Thailand schoolboys rescue - in pictures Thai rescue team members walk inside the cave Rex Features Thailand schoolboys rescue - in pictures An ambulance exits from the Tham Luang cave area AFP/Getty Images Thailand schoolboys rescue - in pictures A military helicopter carrying rescued schoolboys approaches to land at a military airport in Chiang Rai REUTERS Thailand schoolboys rescue - in pictures Rescuers hands locked with a caption reading "We Thai and the international teams join forces to bring the young Wild Boars home" where 12 boys and their soccer coach have been trapped since June 23 in a cave in Mae Sai, Chiang Rai province, northern Thailand. The operation has begun to rescue 12 boys and their soccer coach who will need to dive out of the flooded Thai cave where they have been trapped for more than two weeks, with officials saying Sunday morning that "today is D-Day. AP Thailand schoolboys rescue - in pictures A Thai policeman stands guard at an entrance of the cave as rescue operations continue for 12 boys and their coach trapped at Tham Luang cave at Khun Nam Nang Non Forest Park in the Mae Sai district of Chiang Rai province on early July 8, 2018. Thai authorities told media on July 8 to leave a camp site near the cave where 12 boys and their coach have been trapped for more than two weeks so that "victims" could be helped, possibly signalling a long-awaited rescue effort to get them out. AFP/Getty Images Thailand schoolboys rescue - in pictures Rescuers are seen drillining ahead of the operation at the Tham Luang cave complex, where 12 boys and their soccer coach are trapped, in the northern province of Chiang Rai, Thailand REUTERS Thailand schoolboys rescue - in pictures Rescuers are seen drillining ahead of the operation at the Tham Luang cave complex, where 12 boys and their soccer coach are trapped, in the northern province of Chiang Rai, Thailand REUTERS Thailand schoolboys rescue - in pictures Ruamkatanyu Foundation rescuers are seen drillining ahead of the operation at the Tham Luang cave complex, where 12 boys and their soccer coach are trapped, in the northern province of Chiang Rai, Thailand REUTERS Thailand schoolboys rescue - in pictures Thai policemen stand guard near a cave where 12 boys and their soccer coach have been trapped since June 23, in Mae Sai, Chiang Rai province, in northern Thailand Sunday, July 8, 2018. Thai authorities are racing to pump out water from the flooded cave before more rains are forecast to hit the northern region. AP Thailand schoolboys rescue - in pictures Journalists clear and prepare to leave the cave area during the 'D-Day' for the ongoing rescue operation for the child soccer team and their assistant coach to exit the cave at Tham Luang cave in Khun Nam Nang Non Forest Park, Chiang Rai province, Thailand, 08 July 2018. The officials' operations are underway to safely bring out the 13 members of the youth soccer team including their assistant coach who have been trapped in Tham Luang cave since 23 June 2018, out of the cave according to former Chiang Rai Governor Narongsak Osottanakorn said. EPA Thailand schoolboys rescue - in pictures Thai family members of missing football players and their coach (R) pass to meet with the officers during rescue operations to save a soccer team at Tham Luang cave in Khun Nam Nang Non Forest Park, Chiang Rai province, Thailand, 03 July 2018. According to Chiang Rai provincial Governor Narongsak Osatanakorn rescuers are taking supplies and food into the cave to sustain the team while there extraction is worked out. EPA Thailand schoolboys rescue - in pictures Rescuer walk out from cave where 12 boys and their soccer coach have been trapped since June 23, in Mae Sai, Chiang Rai province, in northern Thailand Sunday, July 8, 2018. Thai authorities are racing to pump out water from the flooded cave before more rains are forecast to hit the northern region. AP Thailand schoolboys rescue - in pictures Policeman line up on the main road leading to Tham Luang Nang Non cave on July 8, 2018 in Chiang Rai, Thailand. Divers began an effort to pull the 12 boys and their soccer coach on Sunday morning after they were found alive in the cave at northern Thailand. Videos released by the Thai Navy SEAL shows the boys, aged 11 to 16, and their 25-year-old coach are in good health in Tham Luang Nang Non cave and the challenge now will be to extract the party safely. Getty Images Thailand schoolboys rescue - in pictures Rescue workers along the main road leading to Tham Luang Nang Non cave as the first 2 ambulances carrying 2 boys pass by on July 8, 2018 in Chiang Rai, Thailand. Divers began an effort to pull the 12 boys and their soccer coach on Sunday morning after they were found alive in the cave at northern Thailand. Videos released by the Thai Navy SEAL shows the boys, aged 11 to 16, and their 25-year-old coach are in good health in Tham Luang Nang Non cave and the challenge now will be to extract the party safely. Getty Images Thailand schoolboys rescue - in pictures Thai medics and police officers evacuate the first two children with a helicopter after rescued from Tham Luang cave before heading to hospital, at a helicopter pad in Chiang Rai province, Thailand, 08 July 2018. Members of a children soccer team and their assistant coach who have been trapped in Tham Luang cave EPA Thailand schoolboys rescue - in pictures An ambulance transporting the children who have been rescued, arrives at hospital in Chiang Rai province, Thailand, 08 July 2018. The first six children have been confirmed to rescue on 08 July 2018 after have been trapped in Tham Luang cave since 23 June 2018. Four members of a children soccer team and their assistant coach who have been trapped in Tham Luang cave since 23 June 2018 have been rescued on 08 July 2018, according to former Chiang Rai Governor Narongsak Osottanakorn said. EPA Thailand schoolboys rescue - in pictures Ambulances transport boys rescued from Tham Luang Nang Non cave to hospital on July 8, 2018 in Chiang Rai, Thailand. Divers began an effort to pull the 12 boys and their soccer coach on Sunday morning after they were found alive in the cave at northern Thailand. Videos released by the Thai Navy SEAL shows the boys, aged 11 to 16, and their 25-year-old coach are in good health in Tham Luang Nang Non cave and the challenge now will be to extract the party safely. Getty Thailand schoolboys rescue - in pictures Medical staff await for the rescued Thai children at Chiang Rai Prachanukroh Hospital in Chiang Rai. The twelve missing Thai children and their adult coach went missing after entering a cave at Tham Luang, in Chian Rai Privince Thailand schoolboys rescue - in pictures Ambulances transporting children after being rescue from Tham Luang cave, arrive Chiangrai Prachanukroh Hospital in Chiang Rai province, Thailand, 08 July 2018. Six children of a child soccer team have been rescued on 08 July 2018 after 12 of them and their assistant coach have been trapped in Tham Luang cave since 23 June 2018. EPA Thailand schoolboys rescue - in pictures Ambulances transporting children after being rescue from Tham Luang cave, arrive Chiangrai Prachanukroh Hospital in Chiang Rai province, Thailand, 08 July 2018. Six children of a child soccer team have been rescued on 08 July 2018 after 12 of them and their assistant coach have been trapped in Tham Luang cave since 23 June 2018. EPA

Workers have been labouring round the clock to pump water out of the cave, which authorities said had offset heavy downpours overnight and prevented the water level within the caves rising.

The rescue operation has involved the boys diving through the cave’s narrow, twisting and jagged passageways while tethered to their rescuers.

The four boys rescued Sunday were happy and in good health, authorities said on Monday evening.

“This morning they said they were hungry and wanted to eat khao pad grapao,” Mr Narongsak said, referring to a Thai comfort food dish of meat fried with chili and basil and served over rice.

The four are undergoing medical checks in a hospital in the provincial capital and were not yet allowed close contact with relatives due to fear of infections. Relatives were able to see them through a glass partition, the governor said.

Seven experienced cave divers from the UK involved in the rescue, expected to take up to four days.

“The UK divers are part of the core team, so they will be actively involved and that will include escorting each child out through the flooded passage,” said a British Cave Rescue Council spokesman.

The death of a former Thai navy Seal on Friday underlined the risks of the operation. Saman Gunan had been working in a volunteer capacity and died on a mission to place air canisters along the boys’ exit route.

The boys and their coach went exploring in the huge Tham Luang Nang Non cave on 23 June after football practice and were cut off when a rainstorm flooded the cave.

A huge search operation was launched, taking 10 days to locate the boys, who had taken shelter on a dry slope deep inside the complex.