Militant Muslims are fighting the government in Indonesia too

It is believed the 13 are being held under Malaysia's Internal Security Act, a law which allows for indefinite detention without trial.

Police have been holding at least 10 other suspected members of the KMM without trial since August last year.

Most of them are members or supporters of the opposition Parti Islam se-Malaysia (PAS), which has denounced the arrests as politically motivated.

'Islamic state'

Malaysia has pledged support to US investigations into the 11 September attacks on New York and Washington.

Prime Minister Mahathir Mohamad has previously said the KMM aimed to topple the government and wanted to establish a hard-line Islamic state comprising Malaysia, Indonesia and the southern Philippines.

In the latest arrests, police said they found documents on guerrilla warfare, map-reading and use of firearms, along with "ideology-related" papers and studies of militant Islamic groups in the southern Philippines, the Russian province of Chechnya, Afghanistan and Indonesia.

Islamic militants have gained a strong foothold in parts of South East Asia.

In Indonesia's Aceh province and the southern Philippine islands, they have been waging separatists wars.

In the Moluccas, members of Laskar Jihad were blamed for whipping up attacks on Christians.

In 2000, extremist members of the Nahdlatul Ulama, pledged to lay down their lives to secure the rule of former President Abdurrahman Wahid.