Russia is arguing strongly against Turkey's demand to keep a leading Kurdish group out of Syria's peace talks.

Russian Foreign Minister Sergey Lavrov said Tuesday that the group, the Democratic Union Party, plays an important role in fighting the Islamic State group and is an essential part of political settlement in Syria.

Lavrov's statement at a news conference comes amid tough posturing ahead of Syria peace talks set to start Friday. U.N. special envoy Staffan de Mistura will be sending invitations amid intense jockeying between countries like Russia and Turkey about who should be invited.

Russia, a key ally of Syrian President Bashar Assad, has called for the inclusion of Kurdish representatives, and the U.S. and others have supported the Kurds in the fight against IS.