Security for former police commando Sirul Azhar Umar has been tightened in the Australian detention centre he is being held amid fears he is being pressured to return to Malaysia to face the death penalty.

Australian prison authorities made the move after a delegation consisting of Sirul Umar’s mother, sister and opposition parliamentarian Mahfuz Omar visited him at Sydney’s Villawood Detention Centre back in March.

Australian daily The Australian said additional security measures have been put in place around Sirul Umar, who was convicted of the 2006 murder of Altantuya Shaariibuu, reportedly the lover of Abdul Razak Baginda, a top aide of then-defence minister Najib Abdul Razak.

The visit was approved by Serco, the contractors responsible for running Australia’s detention centres. The centre was at the time under the control of the Immigration Department.

The Australian reported that Border Force officers found out about the visit after it occurred and are understood to have become highly alarmed amid concerns that Sirul Umar may be vulnerable to intimidation or coercion.

Although officials know the precise reason for the March visit, they are, however, concerned that its purpose was to encourage Sirul Umar to return to Malaysia, where he faces death by hanging.

There are fears that Sirul Umar, or members of his family, could be subjected to intimidation, threats or even physical harm if access to him is not controlled, the daily added.

Sirul Umar a high-risk detainee

The Australian Border Force, which is responsible for security inside detention centres, has determined that Sirul Umar is a high-risk detainee because of his involvement in what, some believe, a murderous conspiracy among Malaysia’s top politicians and officials, The Australian reported.

At the time of Altantuya’s murder and the destruction of her body with the highly-controlled C4 explosives in Shah Alam, Sirul Umar was one of Najib’s bodyguards.

However, Najib, who is now the prime minister, has has repeatedly denied any wrongdoing, or even ever meeting the slain Mongolian woman who acted as a translator in the Scorpene submarine deal with France.

Sirul Umar has been held inside Sydney’s Villawood detention centre since January, after he was picked up by Australian police acting on an Interpol arrest warrant issued by Malaysia.

His detention has created a conundrum for the Australian government, which will not ­deport foreign nationals who face the death penalty in their home countries, raising the prospect of indefinite detention for Sirul Umar.