The six coordinated hotel and church attacks in Sri Lanka which killed nearly 300 people were carried out by a local militant group with international support, senior government officials have said.

Seven suicide bombers carried out the attacks between 8.30am and 9.30am on Sunday at three five-star hotels and three Catholic churches, according to forensic analyses of the blast sites.

"We do not believe these attacks were carried out by a group of people who were confined to this country," Senaratne said. "There was an international network without which these attacks could not have succeeded."

A number of police officers were killed in two explosions later during raids on premises linked to the suspected bombers.

The president of Sri Lanka met with his security council on Monday morning, 24 hours after the blasts that killed at least 290 people and injured more than 450, the majority at sites across the capital Colombo.

Dozens of foreign nationals are understood to be among those killed, including at least eight Britons, according to Sri Lanka’s foreign ministry. The hotels targeted, including the luxury Shangri-La, are among the largest and most popular among tourists in the capital.

Sri Lanka: Scene of the bomb attacks and aftermath Show all 38 1 /38 Sri Lanka: Scene of the bomb attacks and aftermath Sri Lanka: Scene of the bomb attacks and aftermath Sri Lankan Special Task Force officers raid a house following an explosion in capital Colombo AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath A blood-spattered statue of Jesus Christ while crime scene officials inspect the site of a bomb blast, as the sun shines through the blown-out roof, inside St Sebastian's Church in Negombo Reuters Sri Lanka: Scene of the bomb attacks and aftermath A police officer inspects the damage after a bombing at the Shangri-La Hotel in Sri Lankan capital Colombo AP Sri Lanka: Scene of the bomb attacks and aftermath Sri Lankan soldiers look on inside the St Sebastian's Church at Katuwapitiya in Negombo following a bomb blast during the Easter service AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath A woman cries next to a coffin of a bomb blast victim. A series of eight devastating bomb blasts ripped through high-end hotels and churches holding Easter services in Sri Lanka on April 21, killing more than 300 people AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath People who live near the church that was attacked the day before, leave their houses as the military try to defuse a suspected van before it exploded in Colombo Reuters Sri Lanka: Scene of the bomb attacks and aftermath Shoes and belongings of victims are collected as evidence at St Sebastian's Church AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath Sri Lankan police were forded to clear an area while Special Task Force Bomb Squad officers inspected the site of an exploded van near a church the day after it was attacked Reuters Sri Lanka: Scene of the bomb attacks and aftermath The Kingsbury Hotel in Colombo, Sri Lanka following a bombing AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath Queues at the National Blood Bank in Colombo, Sri Lanka after a request for blood to aid in recovery efforts Mr Lavasquabble/Twitter Sri Lanka: Scene of the bomb attacks and aftermath Medical response team work to remove dead bodies from the scene of bombings in Sri Lankan capital Colombo AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath Sri Lankan security personnel inspect the debris of a car after it exploded when police tried to defuse a bomb AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath Security personnel work at the scene of a bombing at a church in Batticaloa in Sri Lanka AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath A woman is helped near St Anthony's Shrine after a blast in Colombo, Sri Lanka, on Sunday 21 April 2019. At least 130 people were killed and more than 500 hospitalised after near-simultaneous explosions hit three hotels and three churches on Easter Sunday. AP Sri Lanka: Scene of the bomb attacks and aftermath Sri Lankan police officers clear the road as an ambulance drives through carrying injured of church blasts in Colombo, Sri Lanka, on Sunday 21 April 2019 AP Sri Lanka: Scene of the bomb attacks and aftermath A Sri Lankan soldier stands guard near a car explosion AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath A woman prays at St. Sebastian's Church in Negombo AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath Priests stand inside St Anthony's Shrine, Kochchikade church on the outskirts of Colombo after a bombing Reuters Sri Lanka: Scene of the bomb attacks and aftermath A Sri Lankan woman living near St. Anthony's shrine runs for safety with her infant after police found explosive devices in a parked vehicle in Colombo AP Sri Lanka: Scene of the bomb attacks and aftermath People react during a mass for victims, two days after a string of suicide bomb attacks on churches and luxury hotels Reuters Sri Lanka: Scene of the bomb attacks and aftermath Security personal react as a device was detonated in a controled explosion in a van near the St Anthony's Church EPA Sri Lanka: Scene of the bomb attacks and aftermath Security forces inspect the scene of a bombing at the Shangri-La Hotel in Sri Lankan capital Colombo Getty Sri Lanka: Scene of the bomb attacks and aftermath The Kingsbury hotel in Colombo, Sri Lanka after a bombing attack Getty Sri Lanka: Scene of the bomb attacks and aftermath The damaged interior of a church in Negombo, Sri Lanka following a bombing attack Reuters Sri Lanka: Scene of the bomb attacks and aftermath Police and security personnel stand guard outside the Shangri-La Hotel in Sri Lankan capital Colombo following a bombing attack EPA Sri Lanka: Scene of the bomb attacks and aftermath Debris is seen at St Anthony's Church in this still image from video footage after explosions hit churches and hotels in Colombo, Sri Lanka, on 21 April 2019 Derana TV/via Reuters Sri Lanka: Scene of the bomb attacks and aftermath Damage inside a church following a bombing attack AP Sri Lanka: Scene of the bomb attacks and aftermath A Sri Lankan Special Task Force officer scales a house during a raid following an explosion in capital Colombo AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath A general interior view showing damage after an explosion hit St Anthony's Church in Kochchikade, Colombo, Sri Lanka, on Sunday 21 April 2019 EPA Sri Lanka: Scene of the bomb attacks and aftermath Priests walk into St Anthony's Shrine Kochchikade church after an explosion in Colombo, Sri Lanka, on 21 April 2019 Reuters Sri Lanka: Scene of the bomb attacks and aftermath A Sri Lankan police officer stands outside St Anthony's Shrine in Colombo, Sri Lanka, after a blast on Sunday 21 April 2019 AP Sri Lanka: Scene of the bomb attacks and aftermath A shoe of a victim is seen in front of the St Anthony's Shrine, Kochchikade Church Reuters Sri Lanka: Scene of the bomb attacks and aftermath Local and security officials gather at the scene at St Anthony's Church in Kochchikade, Colombo, Sri Lanka EPA Sri Lanka: Scene of the bomb attacks and aftermath An ambulance is seen outside the church premises with gathered security personnel following a blast at St Anthony's Shrine in Kochchikade, Colombo, on Sunday 21 April 2019 AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath Armed policemen patrol the area after an explosion hit at St Anthony's Church in Kochchikade in Colombo, Sri Lanka, 21 April 2019 EPA Sri Lanka: Scene of the bomb attacks and aftermath Sri Lankan Army soldiers secure the area around St. Anthony's Shrine after a blast in Colombo, Sri Lanka, Sunday 21 April 2019 AP Sri Lanka: Scene of the bomb attacks and aftermath Sri Lankan security personnel keep watch outside the church premises following a blast at the St Anthony's Shrine in Kochchikade, Colombo, on Sunday 21 April 2019 AFP/Getty Sri Lanka: Scene of the bomb attacks and aftermath Police officers inspect the scene after an explosion hit at St Anthony's Church in Kochchikade in Colombo, Sri Lanka, 21 April 2019 EPA

At midday on Monday local time, forensic teams were still present at at least four of the Colombo bomb sites. Officials say they believe there were seven attackers, but their identities remain unconfirmed and the government has restricted the use of social media in a bid to stop the spread of rumours.

The six attacks were conducted all within a short time window on Sunday morning, as hotel guests were having breakfast and church-goers were attending Easter Sunday masses.

At St Anthony’s church in Colombo, chief priest Jude Fernando told The Independent he believed a suicide bomber had targeted the back of the church where large numbers of people were standing for the final prayers of the service.

Father Jude was by the side of the main altar when the bomb rang out at 8.45am. There were 1,000 to 1,500 people in the church at the time.

“There were so many people inside, we didn’t know what was going on. There were bodies everywhere, people screaming and shouting.

“I can’t understand why the church has been targeted in this way. This is actually a place where everybody comes, regardless of religion, language, caste or creed. This is the most respected place in Sri Lanka, I would say.

"The people who have been injured and killed, they were from all parts of Sri Lanka. This is an attack on the heart of the country. We ask that people remain calm, and for the rest of the world to pray for us.”

Though officials have refused to provide details of the death tolls at individual sites, the Shangri-La, a huge resort in what used to be the Sri Lankan defence ministry complex, was the worst-hit of the three hotels.

Sri Lanka bomb: Dashcam footage showing the blast at Kochikade St. Anthony's church

Unlike the other attacks, two suicide bombers working together are believed to have hit the hotel’s main third-floor restaurant and the corridor outside.

Well over 100 guests were in the restaurant having breakfast at 9.05am when the attack took place, The Independent has learned. The damage is so extensive it can be seen from the main road, with every window blown out and the ceiling collapsed by the force of the two explosions. Forensic teams continued to pick through the mangled mess of plush chairs and dining tables.

At the Cinnamon Grand, the second-largest hotel hit, a security official who asked not to be named said around 50 people were having breakfast when an explosion ripped through the restaurant there.

A man who checked into the hotel under the name Mohamed Azzam Mohamed was queuing up for food at the buffet when he detonated a suicide vest, the AFP news agency quoted a hotel manager as saying.

And at The Kingsbury, 40 guests were eating breakfast when a bomb was set off at around 8.45am, manager Daminda Jayawardena said. He praised duty staff for staying calm and leading guests to safety. Staff brought injured guests to hospital, not waiting for ambulances to arrive.

He said the attack was “devastating”, describing the incident as an assault “on all Sri Lankans”. “The restaurant is badly damaged but for the rest, we hope to be back open tomorrow. Fingers crossed this won’t hurt tourism.”

Two further blasts took place on Sunday throughout the day as police raided homes associated with suspects, one near the zoo to the south of the capital and another in a residential neighbourhood. Three police officers were killed in one of the explosions.

A curfew was in place after nightfall on Sunday and the streets were eerily deserted. Army checkpoints were dotted across the highways to the west of the island nation, and many people were stranded at the international airport, near to which an unexploded pipe bomb was found late in the evening.

Sri Lanka Easter Sunday explosions: What we know so far

It is the worst violence to hit Sri Lanka since the end of the civil war with the Tamil Tigers in 2009. Since then, the country has built up a hard-won reputation for being a safe haven for tourism, and visitor numbers have surged, boosting the economy.

With Sunday’s blasts leading to travel warnings from other countries, including the US and UK, the government is making every effort to conduct a swift investigation and present itself as in control of the security situation. Army officers at checkpoints were apologetic, asking that “no hard feelings” be borne for the inconvenience.

But questions will inevitably be raised over how such a large-scale, coordinated attack could be allowed to take place. Late on Sunday, it emerged that intelligence officials had received warnings in advance.

Sri Lankan Prime Minister Ranil Wickremesinghe said he and other ministers had not been told about the “information regarding a possible attack” and that it had not been acted upon.