Security forces in Singapore and Indonesia combed the undergrowth and traveled on jet skis to outlying islands in a hunt for a top Islamic terror suspect who staged a stunning escape from a high-security jail.

The search for Mas Selamat Kastari stepped into high gear as Interpol, the international police organization, said authorities have lost his trail since he slipped out of a Singapore jail on Wednesday.

Singapore "is a small country, so it's easy to cross and leave," Interpol's chief police services, Jean-Michel Louboutin, told The Associated Press. He said authorities have "no trail for the moment."

On Friday, Interpol issued a high alert to its 186 member states for Mas Selamat, a suspected commander of the Al Qaeda-linked Jemaah Islamiyah's Singapore arm.

Mas Selamat, who is known to walk with a limp, is accused of plotting to hijack a plane and crash it into Singapore's international airport. He was being held under the Internal Security Act, which allows indefinite detention without trial.

Mas Selamat is "someone who presents a potential physical danger to others, but also a potential danger by organizing future bombings," said Louboutin.

On Saturday, special operations officers, elite Gurkha guards and soldiers trudged into central Singapore's forested areas enclosed by a police blockade, while security was tightened at land, air and sea checkpoints.

Dozens of community leaders, including members of Parliament, distributed posters of the fugitive. Wanted notices were displayed at public bus interchanges, train stations and shopping malls.

Security breaches are virtually unheard of in tightly policed Singapore, an island nation of 4 million people that is a 45-minute boat ride from Indonesia where Mas Selamat is alleged to have links with militant groups.

Some 500 policemen were deployed at entry points to Batam, the closest Indonesian island to Singapore, while wanted notices were displayed at seaports, the airport, and on every immigration officer's desk, Batam police chief Col. Slamet Riyanto told the AP.

Security personnel were deployed on jet skis with information on Mas Selamat for residents of the small islands surrounding Batam, said Riau islands police chief Brig. Gen. Sutarman, adding that the suspect knows the islands well and can speak the dialect.

The Singapore government said Mas Selamat escaped because of a "security lapse" at the high security detention center. He had been taken from his cell to a room where he was waiting for his family to make a scheduled visit. He escaped after being granted permission to visit the washroom, authorities said.