Sri Lanka‘s president has vowed to conduct a major shake-up of the country’s security establishment after its failure to prevent the Easter Sunday bombings that killed more than 320 people, despite some officials apparently having prior information about the attacks.

In a televised address to the nation on Tuesday, President Maithripala Sirisena said he would make “major changes in the leadership of the security forces in the next 24 hours”.

He also pledged a “complete restructure” of police and security forces in the “coming weeks”, and alleged intelligence officials had failed to inform him of prior information concerning possible attacks.

“The security officials who got the intelligence report from a foreign nation did not share it with me,” Sirisena said.

Three sources with direct knowledge of the matter said Sri Lankan intelligence officials were tipped off about an imminent attack hours before Sunday’s blasts, Reuters news agency reported on Tuesday.

Indian intelligence officers contacted their Sri Lankan counterparts two hours before the first attack to warn of a specific threat on churches, Reuters reported, citing one Sri Lankan defence source and an Indian government source.

Earlier on Tuesday, Sri Lanka’s Prime Minister Ranil Wickremesinghe also said he received no information regarding a possible attack from security officials, but confirmed authorities had received intelligence about the blasts that struck churches and luxury hotels.

Speaking at a press conference, Wickremesinghe also cautioned that more explosives and would-be attackers remain “out there” after Sunday’s bombings.

Sri Lanka’s failure to effectively respond to the threat has fuelled fears that a rift between Wickremesinghe and Sirisena is undermining national security.

The president fired Wickremesinghe last October over political differences, only to reinstate him weeks later under pressure from Sri Lanka’s supreme court.

ISIL claims responsibility

The Islamic State of Iraq and the Levant (ISIL or ISIS) on Tuesday, meanwhile, claimed responsibility for the attacks. Via its Amaq news portal, it published the noms de guerre of seven people who it said carried out the blasts.

Amaq also released a photo of eight men ISIL said were involved, seven of whom had their faces covered and three of whom held knives.

Sri Lanka’s government has blamed the blasts on a little-known local Muslim organisation, the National Thowheed Jamath, but also said it believed they could not have been carried out without assistance from “international terror groups”.

Wickremesinghe said investigators were making “good progress” in identifying the perpetrators, with police having already arrested 40 suspects, and would be “following up on IS [ISIL] claims”.

“We believe there may be some links,” he added.

The government has imposed a state of emergency, giving police and the military special powers, including the ability to arrest suspects without a court order. It has also rolled out a nationwide curfew and blocked social media channels in a bid to prevent the spread of misinformation online.

National day of mourning

Ruwan Wijewardene, the country’s state minister of defence, said on Tuesday that “preliminary investigations” revealed the bombings were carried out in retaliation for the massacre of 50 Muslims in the New Zealand city of Christchurch last month.

Self-confessed white supremacist Brenton Tarrant, 28, was charged with 50 counts of murder over the mosque shootings.

The office of New Zealand’s Prime Minister Jacinda Ardern said in a statement she was aware of comments linking Sri Lanka’s bombings to the mosque attacks, but added she understood “the Sri Lankan investigation into the attack is in its early stages”.

“New Zealand has not yet seen any intelligence upon which such an assessment might be based,” the statement said.

However, Al Jazeera’s Florence Looi, reporting from the capital, Colombo, said the link between the Christchurch shootings and the Sri Lanka attacks appeared to be “tenuous”.

“Terrorism researchers say there needs to be more caution in making this link simply because the level of sophistication and coordination involved in carrying out the attacks would have taken weeks and months of planning, and there were only five weeks between what happened in Christchurch and what happened on Sunday in Sri Lanka,” Looi said.

The Easter Sunday attacks marked Sri Lanka’s deadliest violence since 2009, when a 26-year-long civil war between ethnic Tamil separatists and government forces ended.

A national day of mourning was held on Tuesday, beginning with a three-minute silence and including the first mass funeral for victims.

The vast majority of those killed in the blasts were Sri Lankan, many from the island nation’s Christian minority.

At least 34 foreign nationals also died in the attacks, according to Sri Lanka’s foreign ministry, with 14 others still unaccounted for and feared dead.