The United Nations on Tuesday sent out invitations for fresh Syria peace talks in Geneva later this week, including to figures excluded from a key opposition body.
"The United Nations Special Envoy for Syria, Mr. Staffan de Mistura, has addressed invitations to the Syrian participants today," his office said in a statement.
It did not specify who had been invited, but several opposition figures confirmed to AFP they had received invitations.
Syria's leading Kurdish party however said it had not yet received an invitation.
Among the invitees are delegates from the High Negotiations Committee (HNC), a body representing key opposition groups and factions that was formed in Riyadh last year.
But invitations have also gone out to several opposition figures who are not in the HNC, which has said it should be the sole opposition delegation at the talks.
Qadri Jamil, a former deputy prime minister who was sacked in 2013 and has good ties with regime ally Russia, confirmed to AFP that he had been invited.
"I am on my way to Geneva after receiving an invitation" to the talks that are scheduled to begin on Friday, he said.
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.
"I received an invitation to participate in the talks as a negotiator," he told AFP.
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A member of the HNC's delegation to the talks, Fuad Aliko, said the body had been invited, but that talks over whether it would attend were continuing.
The HNC has threatened to boycott the negotiations if opposition figures other than its members are allowed to attend.
Syria's most powerful Kurdish party, the Democratic Union Party (PYD), said it had not yet received an invitation.
"Up until now, the PYD has not received an invitation to participate in the Geneva talks," said Sihanuk Dibo, an advisor to the party's leadership.
He said the PYD was in contact with various parties to "resolve the issue in the coming hours or tomorrow."
The PYD is not part of the HNC, and powerful opposition backer Turkey has said it will boycott the talks if the Kurdish party is invited.
Ankara considers it and its armed wing to be an offshoot of the banned Kurdistan Worker's party, which has waged a bloody insurgency in the mainly Kurdish southeast of Turkey since 1984.
Dibo blamed Ankara for the absence of an invite to the talks.
Wrangling over who will represent Syria's opposition has already forced the start of the talks to be delayed from Monday.
The so-called "proximity talks" are scheduled to last six months, with the first round lasting between two and three weeks, according to De Mistura.
They 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.
They are the latest bid to end a conflict that has killed more than 260,000 people and displaced over half of Syria's population since it began with anti-government protests in March 2011.