By Tom Perry
BEIRUT (Reuters) - The Syrian Kurdish PYD party on Tuesday accused opposition groups backed by Saudi Arabia of throwing obstacles in the way of peace talks and said the U.N.-led effort to convene negotiations faced "many hurdles".
PYD co-leader Saleh Muslim, whose party exercises wide influence over Kurdish areas of Syria, also said the United States and Russia must do more to enforce a cessation of hostilities agreement after shelling by insurgent groups killed 16 people in a predominantly Kurdish district of Aleppo.
Diplomats hope the cessation of hostilities agreement, which has brought about a lull in the five-year-long Syria conflict, will allow for peace talks.
The United Nations said on Tuesday it planned to start "substantive peace talks" by March 14, five days later than a previously announced planned start date.
Despite emerging as a major player in Syria, the PYD was excluded from an aborted attempt to hold talks earlier this year, in line with the wishes of Turkey which deems the group part of the PKK - a designated terrorist group in the West.
Muslim, speaking to Reuters by telephone, said his party had yet to receive an invitation this time.
He said the Saudi-backed High Negotiations Committee (HNC) was obstructing efforts by setting preconditions - a reference to its demand for an agenda focused on creating a "transitional governing authority" which would lead to President Bashar al-Assad's removal from office and is opposed by Damascus.
Muslim said the first priority should be to secure a full ceasefire and to agree which armed groups should be deemed terrorists and then discussing the future of Syria, Muslim said.
He said that beyond al Qaeda's Nusra Front and Islamic State - both excluded from the cessation agreement - there were other armed groups in Syria that needed to classified as terrorists.
"The obstacles are emerging from the Riyadh opposition," he said.
ASSAD'S FATE
Assad, buoyed by five months of Russian air strikes, has ruled out demands of opposition groups that he step down, or any other proposal that contravenes the existing constitution.
Muslim said regional states that back the opposition - Turkey, Saudi Arabia and Qatar - "are trying via all tools to thwart the track of the political solution". All three states say they support a political solution to the war.
Syrian rebels fighting Assad view the PYD and the affiliated YPG militia as allies of the Syrian government - a charge denied by the Kurdish groups. The YPG is an important ally of the United States in the war against Islamic State.
Tensions between the YPG and rebels fighting Assad have recently spilled into open war in and around the northern city of Aleppo. Over the weekend, the YPG accused rebel groups of breaching the cessation of hostilities agreement by attacking the Aleppo district of Sheikh Maksoud.
Muslim said "the situation in Sheikh Maksoud is very tragic and needs someone to put an end to it".
Asked about recent Russian statements that federalism could be a possible model for Syria, Muslim said: "What you call it isn't important. We have said over and over again that we want a decentralised Syria - call it administrations, call it federalism - everything is possible".