A Sri Lankan police officer on Tuesday defied President Maithripala Sirisena and testified before a parliamentary investigation into the Easter Sunday suicide bombings that killed 258 people.

Sirisena has come in for major criticism after ordering top brass not to allow police, military or intelligence personnel to take part in hearings into the attacks being held by a parliamentary committee.

The president, who has said the hearings could reveal classified information, is accused by critics of presiding over a security and intelligence apparatus which ignored warnings that could have prevented the attack on three churches and luxury hotels.

On Tuesday the committee heard evidence — much of it in camera — from Inspector N.B.Kasthuriarachchi, who had been in charge of an area where the bombing mastermind was based before he went underground in the months prior to the attack.

Deputy parliamentary speaker Ananda Kumarasiri opened the hearing with a warning to public servants that refusing to cooperate with the committee could lead to a 10-year jail term.

“Anyone who refuses to appear... or withholds any evidence, will be violating the parliamentary privileges act and will be liable to punishment,” he said.

The state telecommunication service provider, which previously broadcast live proceedings of the hearing on cable TV, stopped doing so after a presidential order two weeks ago.

They can still be followed, however, on the parliament website as well as private news channels broadcasting proceedings on social media platforms such as Facebook.

Two weeks ago Sirisena sacked national intelligence chief Sisira Mendis after he testified that the attacks could have been prevented.

Mendis said the president had failed to hold regular security meetings to assess the threat from Islamic radicals who carried out the bombings.

Defence secretary Hemasiri Fernando and police chief Pujith Jayasundara also suggested Sirisena did not follow proper protocol in dealing with a specific intelligence warning from India.

Fernando was forced to resign, while Jayasundara has been suspended from duty.

New Delhi shared detailed information about the targets and method of attack as early as April 4, gleaned from a radicalist in Indian custody, but the intelligence was not acted on.