Devastating Easter bombings in Sri Lanka were retaliation for attacks on mosques in New Zealand, a Sri Lankan official said on Tuesday, as Islamic State claimed responsibility for the coordinated blasts that killed 321 people.

Islamic State’s claim, issued on its AMAQ news agency, came shortly after Sri Lanka said two domestic Islamist groups, with suspected links to foreign militants, were believed to have been behind the attacks at three churches and four hotels, which wounded about 500 people.

Islamic State gave no evidence for its claim. The government has said at least seven suicide bombers were involved.

“The initial investigation has revealed that this was in retaliation for the New Zealand mosque attack,” the junior minister for defence, Ruwan Wijewardene, told parliament.

He did not elaborate on why authorities believed there was a link to the killing of 50 people at two mosques in the New Zealand city of Christchurch during Friday prayers on March 15. A lone gunman carried out those attacks.

Wijewardene said two Sri Lankan Islamist groups — the National Thowheed Jamath and Jammiyathul Millathu Ibrahim — were responsible for the blasts early on Sunday during Easter services and as high-end hotels served breakfast.

US intelligence sources said earlier that the attacks carried some of the hallmarks of Islamic State, even though it had not made an immediate claim of responsibility, as it usually does.

Prime minister Ranil Wickremesinghe told parliament investigators were looking into foreign links.

Earlier on Tuesday, Sri Lankan government and military sources said a Syrian had been detained among 40 people being questioned over the bombs.

The UN Children’s Fund said 45 children were among the dead.

FBI to help

President Donald Trump called prime minister Wickremesinghe on Monday to pledge US support in bringing the perpetrators to justice.

The Washington Post quoted an unidentified law enforcement official as saying Federal Bureau of Investigation (FBI) agents were being sent to Sri Lanka to help with the investigation.

The government had received a tip-off from India this month about a possible attack on churches by the National Thawheed Jama'ut.

It was not immediately clear what action, if any, was taken in response.