NAIROBI (Reuters) - Kenya has suspended nine senior security officials pending an investigation into their handling of this month's attack on a university by al-Shabab militants in which 148 people were killed, the interior minister said on Tuesday.

President Uhuru Kenyatta's government has been under pressure to act over security failures that allowed gunmen from the Somali militant Islamist group to storm Garissa University College on April 2.

"I am convinced of the need for a thorough investigation into the terrorist attack ... to establish possible criminal culpability of individual officers or relevant security committees," Joseph Nkaissery said in a statement.

Those suspended include all police chiefs in Garissa County, its regional administrator and its criminal investigations officer, he said.

The investigative team has been given 14 days to conduct its probe into the attack, Nkaissery added.

"I warn all officers responsible for maintaining security across the country ... (that they) will be held personally accountable for any acts of omission or commission that endanger the lives and property of Kenyans," he said.

The storming of the university was the bloodiest attack on Kenyan soil since the bombing of the U.S. embassy in 1998.

Security experts say Kenya's security forces, which receive support and training from the United States, Britain, Israel and other nations, are hampered by a failure to share and act on intelligence and by poor command structures.

Revelations that journalists and politicians from Nairobi had reached Garissa after the attack before a crack police unit sparked anger and disbelief among Kenyans.

Al-Shabab has now killed more than 400 people in Kenya since Kenyatta took office in April 2013, hurting the east African nation's image abroad and severely damaging its vital tourism industry.

Al-Shabab, which is fighting Kenyan and other African soldiers who are part of a U.N.-mandated African Union force in neighboring Somalia, has repeatedly threatened more attacks on Kenyan soil if the country does not withdraw its troops.