WELLINGTON (DPA) - New Zealand has not seen any intelligence linking the deadly Easter Sunday attacks in Sri Lanka with the mass shooting by a white supremacist in Christchurch last month, Prime Minister Jacinda Ardern's office said on Wednesday (April 24).

Sri Lanka's state minister for defence, Mr Ruwan Wijewardene, said on Tuesday that the suicide attacks on churches and hotels in the capital Colombo and other areas were intended as retaliation for the killing of Muslim worshippers in New Zealand.

"We believe (the massacre) was carried out by an extreme Islamist group as a reprisal for the Christchurch mosque massacre," he said.

"We understand the Sri Lankan investigation into the attack is in its early stages," a spokesman for Ms Ardern said. "New Zealand has not yet seen any intelligence upon which such an assessment might be based."

The Islamic State extremist group claimed responsibility for the bombings in a statement carried by its mouthpiece, Amaq.

The death toll from suicide attacks on churches and hotels over the Easter weekend stands at 321, with the toll still rising as more victims die of their injuries.

The explosions took place during busy Easter services at Christian churches in Negombo, Batticaloa and Colombo, and in three five-star hotels in the capital.

Sri Lankan Prime Minister Ranil Wickremesinghe warned that there are still several suspects at large.