A damning Sri Lankan parliamentary investigation has outlined extensive lapses of intelligence and coordination before the Easter Sunday bombings that killed 269 people, and concluded the spy chief was primarily to blame for the failure to stop the attacks.

The report, released on Wednesday, found the former head of the state intelligence service, Nilantha Jayawardena, had received information about possible attacks as early as 4 April, 17 days before the suicide bombings took place, but was slow to share the intelligence with relevant officials.

It said he was invited to share details of the specific warning of an impending attack at a coordination meeting of leading intelligence officials on 9 April, but Jayawardena said he would include the information in a special report he would send later. The report was not subsequently shared with most of the officials in the room, the committee found.

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The report said the extremist preacher Mohamed Zahran, the alleged ringleader of the attacks, who was among eight terrorists who blew themselves up on 21 April, had been on the radar of authorities from 2015 and an arrest warrant had been issued for him in March 2017.

By 14 April, a week before the attacks, police were conducting searches for Zahran and his known associates. The next day, authorities managed to get his Facebook page removed. An attempt to do so two years before had received no response from the company, the report said.

On 16 April, a motorcycle was blown up in the eastern city of Kattankudy. Jayawardena told the committee he believed the incident was “a dry run” and said he had warned other officials: “You have to take this seriously, because this is definitely a blast. This is Zahran’s activity. We cannot take it lightly.”

Facebook Twitter Pinterest Officials inspect the site of a bombing at the Shangri-La hotel in Colombo. Photograph: Chamila Karunarathne/AP

The day before the attacks, a secret source told Jayawardena an attack would take place some time in the next 24 hours. “They have reported the selected eight places include a church and a hotel where Indians inhabiting a large number. Further details awaited,” the source said.

At 8.27am on the day of the suicide bombings, the same source warned Jayawardena the attacks were likely to take place between 6am and 10am that day. “One of their targets is a methodist church, Colombo,” the source said.

The first blast took place at St Sebastian’s church in Negombo 18 minutes later.

Two more churches and three hotels would be hit in the next hour. Five of the six attacks took place in and around Colombo, the capital. A total of seven suicide bombers died in the attacks, while another blew himself up later, after his explosives failed in a fourth Colombo hotel.

The committee said that if the intelligence officials had been briefed about the threat from Zahran on 9 April, “steps may have been taken to prevent the Easter Sunday attacks”.

The report said the intelligence service did not report to the military about possible attacks until 19 April. The next day, Jayawardena called the national police chief to say there was a high probability an attack would occur on 21 April.

On Easter morning, Jayawardena called the police chief again to say “something dangerous would happen on that day”, the report said. He also called the secretary to the defence ministry, Hemasiri Fernando.

Fernando was quoted in the report as saying that “within a few minutes” of speaking to Jayawardena, he “heard that there had been a bomb explosion at one of the hotels”.

The committee said an open row between the president, Maithripala Sirisena, and the prime minister, Ranil Wickremesinghe, and the ensuing political crisis also contributed to the security failures.

The report said Sirisena failed on “numerous occasions to give leadership and also actively undermined government and systems, including having ad hoc national security council meetings and leaving out key individuals from meetings”.

Facebook Twitter Pinterest The report said a row between Maithripala Sirisena, left, and Ranil Wickremesinghe contributed to failings. Photograph: Ishara S Kodikara/AFP/Getty Images

Sirisena and Wickremesinghe are from traditionally opposing parties but formed a coalition in 2015. They fell out and their conflict was publicly exposed in October 2018 when Sirisena dismissed Wickremesinghe as prime minister. A court decision that restored Wickremesinghe as prime minister ended a 52-day government standstill. But from that point on, Sirisena did not involve Wickremesinghe in security council meetings.

The investigation said no “direct link” had yet been discovered between Zahran and Islamic State, which claimed responsibility for the blasts.

The report’s release coincided with a hard-fought presidential election campaign in Sri Lanka, with Gotabhaya Rajapaksa, the country’s former defence chief, considered the favourite.

Rajapaksa, who is accused of overseeing human rights abuses while serving in the administration of his brother Mahinda Rajapaksa, announced his candidacy in the aftermath of the attacks and has emphasised the restoration of security in his campaign.

The committee, dominated by MPs opposed to the Rajapaksa family, said the extent of the intelligence and police failings raised the question of whether the failure to stop the attacks may have been deliberate.

“Further investigations will be needed to understand whether those with vested interests did not act on intelligence so as to create chaos and instil fear and uncertainty in the country in the lead-up to the presidential election,” it said.

No evidence was provided that any officials had failed to act to stop the attacks for political reasons.

Associated Press contributed to this report