PUTRAJAYA, MALAYSIA: Jemaah Islamiah (JI) militant Mas Selamat Kastari is being detained under the Internal Security Act (ISA) as he is considered a threat to the national security of Malaysia and Singapore.

Prime Minister Datuk Seri Najib Tun Razak said it was Malaysia's decision to detain Mas Selamat and he would be held here "because we need to know more information."

He told reporters yesterday that Mas Selamat's detention under the ISA was the prerogative of Home Minister Datuk Seri Hishammuddin Tun Hussein, who had made the decision.

Asked if the JI leader would be extradited back to Singapore, Najib said he would be held in Malaysia "for the time being."

The 48-year-old militant escaped from a maximum security detention centre in Singapore in February last year and swam to Johor. The fugitive was arrested at his hideout in a tiny Johor village last month.

Asked if Singapore was informed of the decision to detain the man, who had a S$1mil (RM 2.4mil) bounty on his head, Najib said the authorities from both countries were in close contact over the case.

On another matter, the Prime Minister said the Government would not allow former communist leader Chin Peng to return to Malaysia.

"This is because it will cause dissatisfaction among the people, especially family members of those who were killed by the communists during the Emergency," he said.

On April 30, the 85-year-old Chin Peng, whose real name is Ong Boon Hua, failed in his last bid to live in Malaysia after the Federal Court upheld two earlier decisions compelling him to produce his identification documents before he can enter the country.