KUALA LUMPUR: Malaysia will soon introduce a new anti-terrorism law to counter a potential security threat from supporters of the extremist Islamic State (IS) group, Prime Minister Najib Razak said on Wednesday.

Najib told parliament his government also would strengthen existing security-related laws as authorities express mounting concern that Malaysians who have joined the IS in Syria and Iraq will return home to spread militant Islam.

“Looking at the potential threat from this group, we fear the return of Malaysians from the conflict zone in Syria and Iraq will be detrimental to national security,” Najib said.

He expressed concern that returnees will come back with battlefield expertise and could carry out “lone wolf” attacks, but did not elaborate on what the new terror legislation would entail.

Najib made the announcement as he introduced a government white paper on the terrorism threat that said 39 Malaysians had gone to join the fighting in Syria, and that five had been killed.

The document also said that as of Nov 13, authorities had arrested 40 Malaysians at home for suspected IS links.

Twenty-one had been charged with various offences, while the rest were released due to lack of evidence but remain under police surveillance.

In August, police said they had foiled an IS-inspired plot to bomb pubs, discos and a Malaysian brewery of Danish beer producer Carlsberg, arresting more than one dozen people.

Malaysia, which has traditionally observed a moderate brand of Islam, has long kept a lid on extremists. But conservative Muslim views have gained increasing traction in recent years as the long-ruling government's controls have loosened.

Last month, Malaysia's defence minister labelled efforts by the US-led coalition to push back IS fighters in Iraq and Syria as “ineffective”, and called for regional cooperation to prevent militants gaining a foothold in Southeast Asia.

The subject of security laws is controversial in Malaysia, whose government is frequently accused of trampling civil liberties and abusing security-related legislation to silence dissent.