Mas Selamat Kastari

A Singaporean al-Qaida suspect and a member of Jemaah Islamiyah, al-Qaida's Southeast Asia affiliate, escaped from a detention center in Singapore on Wednesday, the government announced.

Mas Selamat bin Kastari, once one of the most hunted terrorist suspects in Southeast Asia, was a confidant of Riduan Isamuddin, better known as Hambali, who was al-Qaida's military commander in Southeast Asia.

Singapore has apologized for the escape that triggered a huge manhunt across the island nation for a man who walks with a limp.

Mas Selamat, who had allegedly plotted to hijack a plane and crash it into Singapore's Changi Airport, slipped away from a detention center on Wednesday, the authorities said. Mas Selamat is said to be commander of the Singapore arm of Jemaah Islamiyah, an Al Qaeda-linked terrorist network.

Minister of Home Affairs Wong Kan Seng said Mas Selamat escaped after being taken from his cell to go to a room to wait for his family, who had been scheduled for a visit.

Mas Selamat was granted permission to visit the washroom and then escaped, Wong said in Parliament.

"This should never have happened," said Wong, who is also the deputy prime minister. "I am sorry that it had. An independent investigation is under way, and we should not speculate on what and how it happened."

Security breaches are virtually unheard-of in Singapore, a small and densely populated island whose sophisticated intelligence system has been liberally used to ensure order and peace.

The security system has taken pride in pre-empting alleged plots to bomb the U.S. Embassy, the American Club and government buildings in 2001. Mas Selamat allegedly had a hand in those plots.

The Home Affairs Ministry said that Mas Selamat was at large after fleeing the Whitely Road Detention Center in a wooded residential area in central Singapore. He walks with a limp, it said.

"Extensive police resources have been deployed to track him down," it said, adding that he was not known to be armed.

A security blockade was thrown around the detention center. The facility - guarded by elite Nepalese Gurkha officers - is enclosed by high fences topped with barbed wire, with closed-circuit television camera surveillance around the perimeter.

Hundreds of police officers and military personnel fanned out, setting up roadblocks to check passing cars. Dozens of riot police trucks were parked along main roads.

It takes less than an hour to drive from one end of Singapore to the other. The country is only a short boat ride from Indonesia and Malaysia.

Indonesian security officials said they would work with Singapore to prepare for the likelihood that Mas Selamat might attempt to go to that country.

Mas Selamat "would think Indonesia is the safest place" to hide, said Nasir Abbas, a former Jemaah Islamiyah operative who now works closely with the Indonesian police.

Musa Hassan, the police chief in Malaysia, said his forces were on the lookout and had informed the border authorities but had not received a broader request to tighten border security.

"We have not received any special request from Singapore as yet," Musa said. "We have not sighted him yet."