Lee, who is also meeting Prime Minister Mahathir Mohamad on September 4, arrived in Malaysia on September 2 to hold four days of informal talks with Malaysian leaders, business people and opinion makers.

"He genuinely seemed concerned that extremist Islamic elements could take root in Singapore like here, saying the battle against this must be kept up relentlessly as this sort of thing can keep cropping up," commented a member of a backbenchers club which met with Lee on September 4.

"He said compared to last year, Southeast Asia was calmer this year with the resolution of political conflicts in the Philippines and Indonesia. But this militancy thing is a new threat," said the legislator, who requested anonymity.

Lee plans to hold a press conference on September 5.

Malaysia's Defence Minister Najib Tun Razak told Lee on September 3 about efforts to bust an Afghan-inspired militant group Kumpulan Mujahidin Malaysia (KMM), which police say is involved in murder, robbery and religious terrorism.

Mahathir said at the weekend KMM had formed networks with likeminded groups elsewhere in the region. Indonesia and Malaysia have Muslim majorities, while other countries in the region, most notably the Philippines, have sizable Muslim minorities.

Ten members of the hitherto unknown KMM were rounded up a month ago and are being held under a security law allowing detention without trial.

One of the men is a son of the spiritual leader of Parti Islam se-Malaysia (PAS), the largest party in Malaysia's mainstream opposition.

PAS says it is against militancy and its leaders say Mahathir is behaving like a dictator and the men should be tried if there is evidence against them.

But Lee, who has described PAS as a potentially destabilising force in the region should it ever win power, was concerned over the links to the Islamic party, according to Domestic Trade and Consumer Affairs Minister Muhyiddin Yassin.

"He stressed this clearly during our discussion," Muhyiddin said, according to Bernama news agency.