If the PYD is invited "then of course we will boycott" the talks in Geneva, Foreign Minister Mevlut Cavusoglu said in a live interview on the private NTV television, adding that the PYD is a "terrorist organisation" which cannot represent Syrian people.

"There cannot be PYD elements in the negotiating team. There cannot be terrorist organisations. Turkey has a clear stance," said the foreign minister.

The United Nations on Tuesday sent out invitations for fresh peace talks in Geneva on Friday but did not specify particularly which groups were called in.

It was not clear if the PYD, Syria's most powerful Kurdish party, had received an invitation.

Turkey, a strong advocate of the Syrian opposition, has opposed the PYD and its armed wing the People's Protection Units (YPG) taking part in the UN-backed talks.

"We are categorically against the YPG and PYD, who oppress the Kurds, sitting at the table," Prime Minister Ahmet Davutoglu told ruling party lawmakers earlier in parliament.

Foreign Minister Cavusoglu, who was in Strasbourg on Tuesday, spoke on the phone with his US and British counterparts, John Kerry and Philip Hammond, diplomatic sources said.

He exchanged views about the peace talks as well as invitations to the meeting, according to the sources.