Syria on Saturday demanded the "immediate and unconditional withdrawal" of Turkish troops that have deployed in the country's northwestern province of Idlib, state media said citing a foreign ministry source.

Turkish troops entered Idlib on Thursday night as part of efforts to enforce a so-called "de-escalation zone" agreed by rebel backer Ankara and regime allies Russia and Iran at talks in Astana earlier this year.

But the Syrian foreign ministry source slammed the "Turkish aggression", saying it had "nothing whatsoever to do with the understandings reached by the guarantor countries in the Astana process."