COLOMBO (AFP) - Sri Lanka's ex-president and his intelligence chiefs should be prosecuted for failing to prevent suicide bombings two years ago on Easter Sunday that killed 279 people, according to an investigation released on Tuesday (Feb 23).

Maithripala Sirisena, who left office last year, was found to have been negligent by an investigation he set up five months after the Islamic militant attacks on three hotels and three churches on April 21, 2019.

It quickly emerged that Indian intelligence had warned Sri Lanka 17 days beforehand about the risk of attacks, following a tip-off from a suspect.

The report by the presidential commission of inquiry said the "balance of probability" was that Sirisena was told by his intelligence chief about the warnings before the attacks.

The commission, which heard from 440 witnesses and handed over its report to parliament on Tuesday, said the attorney general should "consider instituting criminal proceedings against (former) president Sirisena under any suitable provision in the Penal Code".

Sirisena, now a ruling party legislator, has previously denied any knowledge of the warnings, and made no comment about the report.

The probe also found Sirisena's head of intelligence Nilantha Jayawardena was criminally liable for failing to act on the warnings from Indian intelligence.

Jayawardena had "diluted the weight of the intelligence" from India, the report said.

It added that police inspector-general Pujith Jayasundara should also be prosecuted for negligence.

Jayasundara and the top defence ministry official at the time, Hemasiri Fernando, already face charges over their failure to prevent the attacks.

The report found that the coordinated bombings were funded by the family of a local spice trader whose two sons were among the suicide bombers.

Two days after the attack, the Islamic State group claimed responsibility, but investigators say they have not found a direct link between the local jihadists and IS.

The attacks were led by Zahran Hashim, an Islamist known to Sri Lankan anti-terror police and intelligence units.

He had issued calls on social media for the killing of non-Muslims and persuaded six young men to sacrifice themselves in the Buddhist-majority nation.

The spice trader's son, Ilham Ibrahim, died at the Shangri-La Hotel while his brother Inshaf Ibrahim bombed the Cinnamon Grand. Ringleader Hashim also died at the Shangri-La.

Two churches in Colombo and another in the eastern region of Batticaloa were also hit by suicide bombers.