The Islamic State has claimed that it was behind the horrific suicide bombings of churches and luxury hotels in Sri Lanka over the Easter weekend.

The terrorist group made the claim through its official Amaq news agency on Tuesday.  

It comes after Sri Lankan intelligence named radical local cleric Moulvi Zahran Hashim as the chief mastermind of the Easter Sunday attacks. He reportedly used his social media channels in the past to incite hatred against non-Muslims. 

Senior government officials had blamed the little known radical Islamist group, the National Thowheed Jamath (NTJ), which gained prominence last year after being accused of damaging Buddhist statues. 

Government spokesman Rajitha Senaratne previously said that whoever carried out the attacks must have been helped by an international network. 

"We do not believe these attacks were carried out by a group of people who were confined to this country," he said.

"There was an international network without which these attacks could not have succeeded."

The devastating attacks were carried out on two Catholic churches and one evangelical church that were packed with worshippers celebrating Easter Sunday.

Four luxury hotels were also targeted in the attacks that claimed the lives of 321 people, including eight British citizens.

Defence minister Ruwan Wijewardene told lawmakers in parliament on Tuesday that he believed the bombings were in retaliation for the recent attack on two mosques in Christchurch, New Zealand.  Fifty people were killed when a gunman opened fire in the mosques on March 15. 

"The preliminary investigations have revealed that what happened in Sri Lanka was in retaliation for the attack against Muslims in Christchurch, but we are continuing investigations," Wijewardene said.