Malaysian police have stepped up security, particularly around areas linked to Russian and Western interests, following reports that Syrian militants who infiltrated Thailand may target such locations.

The Star newspaper yesterday quoted Inspector-General of Police Khalid Abu Bakar as saying Malaysia was beefing up its security, although the police have not had any intelligence reports of similar attacks being planned in the country.

"We will strengthen security to ensure that no attack takes place in the country. We will also closely monitor Russian interests in the country," Tan Sri Khalid said.

He was responding to reports of a leaked Thai police memo revealing that 10 members of the Islamic State in Iraq and Syria (ISIS) had entered the kingdom between Oct 15 and 31, with four of them having travelled to Pattaya, two to Phuket, two to Bangkok and two others to unknown locations.

According to the memo, the Russian Federal Security Service had urged the Thai authorities to elevate security around locations that are linked to Russia or its allies taking part in air strikes in Syria.

Mr Khalid said in a statement yesterday that police have arrested five men - four foreigners and a Malaysian - suspected to have links to terrorist groups ISIS and Al-Qaeda. They were arrested in various places between Nov 17 and Dec 1.

Three of them - an Indonesian mechanic, 31, a Malaysian tailor, 59, and a Bangladeshi technician, 25 - are believed to be part of a terror cell that has links with ISIS.

The Indonesian, the cell leader, had pledged allegiance to ISIS head Abu Bakr al-Baghdadi, via Facebook last year, and keeps in contact with a few Malaysians who have joined ISIS in Syria.

"He is believed to have acted as a facilitator for individuals from Malaysia and South-east Asia who wish to join ISIS and other terror groups in the region," said Mr Khalid.

The other two detainees are an African college student, 29, and a European teacher, 44.