Nine Kenyan security officials from Garissa have been suspended and could face charges of criminal negligence over the massacre at the town’s university earlier this month, the government announced Tuesday.

Militants from Somalia’s al-Qaeda-linked Shebab militants attacked the university in the northeastern town of Garissa on April 2, lining up non-Muslim students for execution and killing 148 people.

Kenya interior minister Joseph Nkaissery said a preliminary investigation into the response to the attack signalled that the officials, among them senior police officers, had failed to mobilise ahead of the attack despite intelligence warnings.

"I take this opportunity to warn all officers bestowed with the responsibility for the management of security across the country. Each will be held accountable for any acts of omission that endangers the lives and property of Kenyans,” the minister told reporters.

"This investigation is starting immediately,” he added, saying that the officials would be formally charged if there is evidence of negligence.

The Kenyan government and the country’s security forces have come in for renewed criticism following the massacre, with Kenyan media alleging that warnings were ignored and response times by special forces were slow.

Nkaissery, however, played down a controversy surrounding the use of a special police plane to transport the family of a senior police official back from their holiday on the coast on the day of the attack.

According to local media reports, elite anti-terror police had to wait several hours for the plane to pick them up from Nairobi for the Garissa mission.

But the interior minister insisted the plane was in the coastal region anyway on "an official training mission, and on its way back it gave a lift to the family” of the police air wing commander. He said this was authorised and did not affect the massacre response time.

The Garissa massacre was the deadliest attack on Kenya since the 1998 bombing of the US embassy in Nairobi.