Islamic State has said it carried out the Sri Lanka suicide bombings which have killed at least 321 people, as mass burials are held for the victims.
The extremist group made the claim via its Aamaq news agency and said the perpetrators of the attacks were "fighters from the Islamic State", but offered no evidence to support the claim.
The death toll has risen to 321 and 500 people injured in the near-simultaneous bombings on Easter Sunday.
The majority of the bombings took place in around the capital Colombo, but a church was targeted in Negombo, a town north of the capital and in the eastern town of Batticaloa.
At least 45 children were killed in the blasts, the UN children's agency has said.
Unicef said on Tuesday that 27 children died and 10 were injured in the bombing of St Sebastian's Church in Negombo, 13 died in Batticaloa, and among the foreign victims, five were children.
IS claims to have identified the attackers who carried out the bombings, but only gave out the nom de guerre and did not specify the nationalities of the suicide bombers or provide photographs or videos of the attackers.
A defence minister has said the initial investigation shows the suicide bombings in Sri Lanka were meant as revenge for the Christchurch mosque shooting in New Zealand.
Ruwan Wijewardene told Parliament the attacks were "carried out in retaliation", without providing evidence or explaining where the information came from.
Mr Wijewardene said local Islamist group National Thawheed Jama'ut (NTJ) was responsible for the attack.
However New Zealand's prime minister, Jacinda Ardern, has said she has not seen any evidence linking the Sri Lanka suicide bombings to the Christchurch shooting, which killed 50 people in March.
Police have arrested 40 suspects and are still investigating how the attackers managed the near-simultaneous explosions.
Mass funerals are taking place in Sri Lanka for some of the victims on Tuesday, which has been declared a national day of mourning.
Flags were lowered and the country observed a moment of silence at 8.30am - the time when the first attack was carried out.
People across the country bowed their heads to remember the victims and those injured in the devastating bombings.
A funeral service was held at St Sebastian's Church in Negombo, north of Colombo, the scene of one of the Easter Sunday bombings.
A state of emergency was in effect on Tuesday, giving the Sri Lankan military war-time powers and a wider berth to detain and arrest suspects - powers last used during the country's civil war.
Among the arrested is the driver of a van allegedly used by suicide bombers and the owner of a house where some of them lived, officials said.
Authorities were reportedly warned about an imminent threat in the weeks before the attack, as Sri Lanka's leadership comes under scrutiny.
- Who knew what ahead of the attacks?
The warning in an April 11 letter was clear - a local group was planning a suicide terror attack against churches in Sri Lanka.
Security forces were reportedly alerted to the threat of militant group NTJ from the deputy inspector general of police, Priyalal Disanayaka.
In the letter he said the group was planning a suicide attack in the country and named six individuals likely to be involved in the plot.
But the information was not passed to Prime Minister Ramil Wickremesinghe and his government, ministers said.
Health minister Rajitha Senaratne said because of political infighting between the prime minister and President Maithripala Sirisena, the warnings were not heeded.
Cardinal Malcolm Ranjith, the archbishop of Colombo, said the attacks could have been thwarted.
"We placed our hands on our heads when we came to know that these deaths could have been avoided. Why this was not prevented?" he said.
Mr Wickremesinghe said on Tuesday there are more militants "out there", as he revealed some officials will likely lose their jobs over intelligence lapses surrounding the attack.
The prime minister acknowledged there was a prior warning, and said India's embassy was eyed as a possible target.
- What do we know about National Thowfeek Jamaath?
The government named NTJ as one of the Islamist's group to have carried out the attack.
However it is unclear how a little-known group managed the six near-simultaneous suicide bombings on Easter Sunday.
The purported leader of an Islamic extremist group blamed for the attack began posting videos three years ago calling for non-Muslims to be "eliminated", faith leaders have said.
NTJ’s leader, alternately known as Mohammed Zahran or Zahran Hashmi, became known to Muslim leaders three years ago for his incendiary speeches online.
Zahran's name was on one intelligence warning shared among Sri Lankan security forces
Muslim leaders say repeated warnings about the group and its leader drew no reaction.
Authorities said they knew where the group trained and had safe houses, but did not identify any of the suicide bombers, whose bodies were recovered, or the two dozen other suspects taken into custody.
All the bombers were Sri Lankans, but authorities said they strongly suspected foreign links, Health minister Rajitha Senaratne said.
ITV News Security Editor Rohit Kachroo believes the level of scale and coordination National Thowfeek Jamaath suggests it had help from groups outside of Sri Lanka.
He added that Sri Lanka has a well-developed and sophisticated counter-terrorism structure, suggesting that it could be part of an international network, carrying out attacks on the orders of a larger terrorist network such as Al-Qaeda or so-called Islamic State.
- What happened on Sunday?
The six near-simultaneous explosions took place shortly before 9am local time on Sunday morning - three at churches and three at luxury hotels.
St Anthony's Shrine in Colombo was targeted and three luxury hotels - the Cinnamon Grand, Shangri-La and Kingsbury.
St Sebastian's Church in Negombo, a majority Catholic town north of Colombo, and Zion Church in the eastern town of Batticaloa, were the other churches hit by the explosions.
A few hours later, two more blasts occurred just outside of Colombo, one of them at a guesthouse, where two people were killed, the other near an overpass.
Three police officers were killed during a search at a suspected safe house on the outskirts of Colombo when its occupants apparently detonated explosives to prevent arrest.