Prime Minister Imran Khan, in a telephone conversation with his Sri Lankan counterpart Ranil Wickremesinghe on Wednesday, strongly condemned the string of bombings in Sri Lanka that claimed the lives of at least 359 people.

The prime minister conveyed his heartfelt condolences to the bereaved families and prayed for the speedy recovery of the wounded.

Prime Minister Imran said that the people of Pakistan are deeply grieved over the loss of precious lives and "stand with their Sri Lankan brethren at this hour of grief."

The prime minister said that terrorism knows no boundaries, no religion and threatens the peace of entire region and the world.

He said that Pakistan condemns terrorism in all its forms and manifestations and will continue to provide every possible support for elimination of this menace.

He also reiterated Pakistan’s offer of assistance to Sri Lanka towards counter terrorism measures.

Read more: Pakistan helped Iraq in defeating IS, says Iraqi envoy

No word from SL yet: NZ PM

Sri Lanka's leaders have vowed to overhaul the security apparatus amid a series of intelligence lapses before the attacks. They have said that some of the country's security units were aware before Easter of possible attacks, but did not share those warnings widely.

In an address to Parliament, Ruwan Wijewardene, the state minister of defence, said “weakness” within Sri Lanka's security apparatus led to the failure to prevent the nine bombings.

“By now it has been established that the intelligence units were aware of this attack and a group of responsible people were informed about the impending attack,” Wijewardene said.

“However, this information has been circulated among only a few officials.”

The government has said the attacks were carried out by Islamic fundamentalists in apparent retaliation for last months' New Zealand mosque massacre but maintains that the seven bombers were all Sri Lankan. A local extremist group, National Towheed Jamaat, was initially suspected to be behind the attacks.

The militant Islamic State group claimed responsibility for the attacks and released images that purported to show the seven bombers who targeted three churches and three hotels on Sunday in the worst violence the island nation has seen since its civil war ended a decade ago. The group did not provide any other evidence for its claim, and the identities of those depicted in the image were not independently verified.

New Zealand Prime Minister Jacinda Ardern told reporters in Auckland today that she'd had no official word from Sri Lanka, or seen any intelligence reports, to back that up. However, she added that Sri Lanka was in the early stages of its investigation.

No prior info about attacks: US

US Ambassador Alaina Teplitz, meanwhile, told reporters that “clearly there was some failure in the system.”

Teplitz said the US had “no prior knowledge” of a threat before the bombings. She said a team of FBI agents and US military officials were helping in the investigation.

The IS has lost all the territory it once held in Iraq and Syria and has made a series of unsupported claims of responsibility around the world.

Teplitz declined to discuss whether the embassy or US officials had heard of National Towheed Jamaat or its leader prior to the attack. “If we had heard something, we would have tried to do something about this,” Teplitz said.