THE Jemaah Islamiah leader who escaped from the Whitley Detention Centre on Wednesday afternoon was on his way to meet his family who was visiting him when he gave his escorting officers the slip.

Home Affairs Minister Wong Kan Seng disclosed the circumstances behind Mat Selamat Kastari's escape from the centre when he was questioned in Parliament on Thursday afternoon.

His family was visiting him at the time, and he was being led to a room to meet them when he asked to go to the toilet.

He then fled.

Giving an update of what happened, Mr Wong also apologised for the 'security lapse at the Whitley Detention Centre'.

'This should never have happened. I am sorry that it had. An independent investigation is underway and we should not speculate on what and how it happened,' he said, adding that security at the centre had since been stepped up.

Mat Selamat was taken out of his individual cell where he was confined to go to the family visit room to wait for his family to arrive. However, before he got there, he asked to go to the toilet, and that was where he fled.

Mr Wong added: 'He is a security threat which is why he was placed under preventive detention, However, there is no information that he has any plans that threaten public security. Nevertheless, we are not taking any chances.'

On why the public was informed of the escape only four hours after the escape, Mr Wong said the escape posed no 'imminent danger to the public' at the time.

'The focus then was to lock down the Whitley Road detention centre and then to start a systemic operation to find and arrest him. The priority is to arrest him and no effort will be spared to track him down,' he said.

Elaborating, he added that the security at all the air, land and sea checkpoints have been tightened, including 'the areas where he may leave our shores not from the normal immigration clearance areas'.

He also warned that anyone who helps Mat Selamat would be committing a serious offence. 'I urge the public to stay calm and report any suspicious sightings to the police immediately,' he said.