Thai police have received a warning from Russia’s state security agency that 10 Syrians linked to the Islamic State of Iraq and the Levant (ISIL) group could stage attacks in Thailand on targets associated with Russia and others opposed to the armed group, officials have said.

National police deputy spokesman Colonel Songpol Wattanachai confirmed on Friday the authenticity of a leaked police memo mentioning the intelligence warning. He told reporters that the information has not been verified.

The police memo – dated November 17 and marked “urgent” and “confidential” – cites Russia’s Federal Security Service (FSB) warning that the 10 Syrians believed to be involved with ISIL entered Thailand in the second half of October. According to the memo, some of them went to Bangkok, Pattaya, and Phuket.

Pattaya and Phuket are seaside resorts popular with foreign tourists, and Pattaya is especially popular with Russians.

“The objectives of these people are to cause harm to Russia’s assets or those of its allies in Thailand,” said the memo.

The police memo called on security officials to confirm the information and step up security at possible targets related to countries opposed to ISIL, specifically the United States, Britain, France, Germany, Sweden and Australia.

Tight security

Songpol also said that security had already been increased at venues in Bangkok, including embassies, after the deadly attacks in Paris on November 13.

The Thai capital was the target of a bombing in August that killed 20 people, but the attack has been linked to rebels from China’s Muslim Uighur minority.

There have been few signs of ISIL activity in Thailand, though the group actively recruits volunteers from its Southeast Asian neighbours Malaysia and Indonesia – which are predominantly Muslim – to fight in Syria and Iraq.

Sidney Jones, an expert on Southeast Asian Islamist movements at the Jakarta-based Institute for Policy Analysis of Conflict, told the AP news agency that ISIL cells in Southeast Asia were getting more serious about establishing a more formal structure.