SINGAPOREAN authorities have received more than 1,100 tips from the public in its manhunt for an alleged terrorist leader who escaped jail two weeks ago, police said.

Mas Selamat bin Kastari, the alleged Singapore head of Jemaah Islamiah (JI) which is blamed for deadly attacks including the 2002 Bali bombings, vanished on Feb 27 after asking to use the toilet in his detention centre.

The more than 1,100 phoned-in tips had been received from the public as of Monday after police asked for information leading to Mas Selamat's arrest, police director of operations Wong Hong Kuan said on Wednesday.

Security forces were still conducting searches almost island-wide, with a focus on forested tracts though it was not 'neglecting the urban built-up areas', Mr Wong said.

The search - involving police, the military and Nepalese Gurkha paramilitary forces - is the biggest manhunt in the history of Singapore, which has lush nature reserves and densely populated housing blocks.

Pictures of the wanted man have been plastered across the island and sent to mobile phone subscribers.

Security forces in neighbouring Indonesia and Malaysia were also on the lookout for Mas Selamat, but Singapore insists he is unlikely to have fled the island.

Prime Minister Lee Hsien Loong said on Sunday that Singapore remained optimistic it can capture him.

'I've been talking to the ministers responsible and I think we have a pretty good chance of catching him provided he's still in Singapore,' Mr Lee said.

Former Prime Minister Lee Kuan Yew, earlier said Singapore should brace itself for an attack if Mas Selamat manages to flee the city-state and rejoin his JI comrades.

Mas Selamat, 47, was accused of plotting to hijack a plane in order to crash it into Changi Airport in 2001, but he was never charged in court.

He was being held under an internal security law that allows for detention without trial.

Interpol has issued an international red alert for him. -- AFP