At least 50,000 Malaysians support the Islamic State of Iraq and the Levant (ISIL) group, the country's transport minister said on Saturday, raising alarm about possible attacks in the Southeast Asian nation.
The figure of 50,000 ISIL supporters was based on police intelligence estimates, Transport Minister Liow Tiong said.
"If only one percent of these sympathisers turn radical and if they attack any part of Malaysia, we will be in trouble," Liow told a conference in Kuala Lumpur on national security and the ISIL threat.
About 100 Malaysians have gone to Syria and Iraq to fight with ISIL and other armed groups, according to police.
Anti-terrorism police have charged more than two dozen ISIL sympathisers in court.
'Imminent terrorist threat' reported in Malaysia
In November, Malaysia deployed 2,000 soldiers on the streets of Kuala Lumpur after unconfirmed reports of an "imminent terrorist threat" raised alert level.
A police memo, leaked to local media, detailed the presence of at least 10 potential suicide bombers in Kuala Lumpur and eight elsewhere in the country.
The document revealed details of a meeting between members of the armed Philippine groups - the Moro National Liberation Front and Abu Sayyaf - along with those from ISIL.
An agreement at the meeting was made to deploy Abu Sayyaf and ISIL fighters to Kuala Lumpur and to Sabah, Malaysia's eastern-most state, the memo said.