Singapore - Complacent guards were negligent in the break-out of accused terrorist Mas Selamat Kastari after the suspect lulled them into believing they had him under control, Minister Mentor Lee Kuan Yew said in a published report on Saturday.

Mas Selamat, whom Lee called an "escape artist," has been at large for more than five weeks.

"When you are complacent in handling a wily detainee, then you have been negligent," Lee told The Straits Times.

Mas Selamat, 47, accused of planning to hijack a plane and crash it into Changi Airport in 2001, escaped from an Internal Security Department detention centre on February 27 when he was granted permission to use a bathroom.

The search for the man who headed the Singapore cell of the Jemaah Islamiah (JI) Islamic terrorism network has moved into a more targeted and focused phase, based on specific intelligence and leads obtained by police.

Mas Selamat's guards believed they had the "measure of him" and that he would not get the better of them, said Lee, Singapore's founding prime minister.

"He was an escape artist, evading arrest in Singapore, Malaysia and Thailand, and then in Indonesia," Lee said. "Our security officers knew his history. Yet he was able to lull them into a sense of security, that they had him under control. Then he gave them the slip."

"If they had respected his skills in dissimulation and viewed him with skepticism, they would have not allowed him to spring surprises on them," Lee noted.

Police believe Mas Selamat is still hiding in Singapore, but Indonesian and Malaysian authorities are keeping watch.

Singaporeans who believe nothing can go wrong in the city-state are "living in a make-believe world," Lee said. "There is no country in the world where nothing goes wrong."

"Complacency sets in when a people have not suffered any shock or setback for a long time, as in Singapore without jihadist terror attacks, although we have ceaselessly talked about it and prepared out defences," Lee said.

"Most people believe that bad things will happen to others, not to themselves," he added.

Mas Selamat was turned over to Singapore by Indonesia in 2006. He had been held under a law allowing for detention without trial.

Interpol has issued an international alert for the fugitive. (dpa)