Ten Syrians "related to" Daesh group entered Thailand in October to attack Russian interests, Thai police said in a leaked document citing information from the Russian Federal Security Service, according to the Daily Mail.

In the document, Special Branch police urged an intensification of security around "target areas that Russian authorities are concerned about" including venues associated with allies that have taken part in attacks on Daesh in Syria.

Russia began air strikes in Syria on Sept. 30 and has stepped up attacks in recent weeks. An affiliate to the so-called Islamic State claimed responsibility for downing a Russian airliner over Egypt in October, killing all 224 people on board.

Thailand's Special Branch, which deals with national security issues, circulated the document to other police units, two senior police officers told reporters.

Marked "Urgent" and dated Nov. 27, the Special Branch police said intelligence from Russia warned that the 10 Syrians entered Thailand between Oct. 15 and Oct. 31. The document was circulating on social media on Thursday.

"The document is real. We received it from Special Branch," said one of the police officers, who handles international crime matters. He declined to be identified because of the sensitivity of the matter.

Sources: MENA