SINGAPORE (AFP) - - Singapore has sacked the superintendent of a detention centre where an alleged extremist leader escaped through a toilet window, the interior minister said Monday, while his deputy has been demoted.

Two elite Nepalese Gurkha guards who had escorted Mas Selamat Kastari to the toilet were also demoted, Home Affairs Minister Wong Kan Seng told parliament.

Kastari, the alleged Singapore leader of the extremist group Jemaah Islamiyah (JI), made his escape from Whitley Road Detention Centre on February 27 after asking for a break during a visit by family members.

His flight punctured Singapore's reputation for solid security and sparked the biggest manhunt in the country's history.

Kastari remains at large and is believed to have fled to neighbouring Indonesia, where other JI leaders are suspected to be based.

The superintendent and his deputy were the two most senior officers in charge of "ground management" at the centre, which is run by the Internal Security Department, Wong said.

The pair were "held accountable for the lack of supervision over the subordinate officers implicated, which resulted in lapses" that enabled Kastari to escape, the minister said.

A special duty operative, her supervisor, two other officers and the chief warder were also disciplined, Wong said.

An inquiry into the escape cited windows without grilles, surveillance cameras that were not working and a slow reaction from guards as likely contributing to Kastari's flight.

Kastari was accused of plotting to hijack a plane in order to crash it into Singapore's Changi Airport in 2001 but was never charged. He was being held in the city-state under a law that allows for detention without trial.