ANKARA (Reuters) - Turkey designates both Islamic State and the Nusra Front, now known as Jabhat Fateh al-Sham, as terrorist groups and acts in line with that policy, a Turkish foreign ministry source said on Thursday.

Jabhat Fateh al-Sham launched an attack on a number of Free Syrian Army (FSA) rebel groups in northwestern Syria on Tuesday, threatening to deal a critical blow to the more moderate wing of the Syrian rebellion backed by Turkey and to derail Russian-backed peace talks.

The attacks may have been motivated by Jabhat Fateh al-Sham's desire to prevent a political solution to the Syrian conflict, the source said.

The source also said Turkey was not aware of any constitutional draft presented by Russia during the peace talks this week in the Kazakh capital Astana that included autonomy for Syria's Kurds, the source also said.

(Reporting by Tulay Karadeniz; Writing by Humeyra Pamuk; Editing by Nick Tattersall)