Beirut:An important section of the Syrian opposition has to decide Wednesday on whether to participate in the Geneva peace talks which could be compromised by the presence of other opponents of the regime including the Kurds.

The office of UN Syria envoy Staffan de Mistura said it had issued invitations to the talks scheduled to begin on Friday but refused to say who had been invited to represent President Bashar al-Assad and the Syrian opposition.

It is the latest international attempt to end Syria's conflict which has killed more than 260000 people since it began with anti-government protests in March 2011.

The talks have already been delayed from their scheduled start on Monday over who will represent the opposition.

The High Negotiations Committee a body representing key opposition groups and factions insists it should be the sole opposition delegation.

But several opposition figures who do not belong to the body told AFP on Tuesday they had been invited to the talks.

The HNC met in Riyadh to debate whether it would attend with a source close to the meeting confirming the body had received invitations to Geneva but discussion on whether to participate was ongoing.

"The response will be a request for clarifications and not an acceptance or rejection" he told AFP adding that the body wanted to know who else had been invited and under what terms as well as what would be discussed.

HNC member Salem al-Meslet said the group would resume talks from 10:00 am (0700 GMT) on Wednesday adding that the "climate is positive".

The HNC will also "ask tomorrow for clarifications (from the UN) concerning some issues particularly humanitarian issues" he said.

- Turkey threatens boycott -

Several opposition figures who are not part of the HNC said they have been invited.

"I am on my way to Geneva after receiving an invitation" said Qadri Jamil a former deputy Syrian premier who was sacked in 2013 and has good ties with Russia.

And Haytham Manna a longstanding opposition figure who is co-chair of the political wing of a Kurdish-Arab alliance also said he had been invited.

Syria's most powerful Kurdish party the Democratic Union Party (PYD) said it had not yet received an invitation.

Sihanuk Dibo an adviser to the party's leadership said the PYD was in contact with various parties to "resolve the issue in the coming hours or tomorrow (Wednesday)".

The PYD is not part of the negotiations committee and leading opposition backer Turkey has said it will boycott the talks if it is invited.

Ankara considers the party and its armed wing to be an offshoot of the banned Kurdistan Worker's party (PKK) which has waged a bloody insurgency in the mainly Kurdish southeast of Turkey since 1984.

"There cannot be PYD elements in the negotiating team. There cannot be terrorist organisations. Turkey has a clear stance" Turkish Foreign Minister Mevlut Cavusoglu said Tuesday.

But earlier Russia's Foreign Minister Sergei Lavrov warned that the talks "cannot achieve the results we want a definitive political resolution in Syria" if the PYD is excluded.

French Foreign Minister Laurent Fabius said there were "very difficult questions to resolve about the composition of the delegations" at the talks.

But he insisted that "there is one simple rule one party cannot demand the make-up of another delegation".

The talks are part of a UN-backed plan agreed last year that envisages negotiations followed by the creation of a transitional government a new constitution and elections within 18 months.

Delegations are expected to engage in "proximity talks" rather than face-to-face discussions which will run over six months.

The first round is expected to last between two and three weeks.

The talks come as government forces have made several key military gains in recent weeks assisted by Russian air strikes in support of regime troops.

AFP