Image copyright Getty Images Image caption Those involved reportedly worked at entrance gates at Malaysian airports (file image)

Malaysia has fired 15 immigration officers, accusing them of sabotaging passport systems to let in certain travellers undetected.

Suspicions were raised after computer systems at Malaysian airports crashed several times a day.

The 15 are accused of deliberately taking them offline, allowing people to bypass criminal background checks.

Another 65 officers have been redeployed, while a new roster will now monitor immigration points.

As many as 100 immigration officials may have been involved in the operation, investigators say.

The country's passport system may have been compromised for the past two years, according to the Malaysian authorities, possibly benefiting people traffickers and militant networks.

During that time both the British and Australian governments raised their terror alerts for Malaysia, warning of possible attacks in and around the capital Kuala Lumpur.

It is not clear how those accused were able to sabotage systems. Technological problems were initially suspected as causing the crashes.

"All the officers and staff involved in the disciplinary action are from various support level service schemes, stationed at the main entrance gates into Malaysia," the Immigration Director-General Datuk Seri Sakib Kusmisaid said, according to the New Straits Times.

Those involved are thought to have done it for financial gain.