Syrian Kurdish leaders were expected to declare a separate federal region in northern Syria, a move that the United States signaled it would not recognize.
The move was likely to complicate efforts by Washington to keep a united front with Turkey in the fight against Islamic State fighters, who still control substantial parts of Syria and Iraq.
Kurdish forces have been among the most effective battlefield units in fighting Islamic State, and Turkey, with a large and restive Kurdish population of its own, fears the creation of an autonomous Kurdish state could threaten its own borders.
Syrian Kurdish political groups said they made the decision to seek a federal state after being excluded so far from United Nations-brokered peace talks between the Syrian government and the opposition in Geneva.
Nawaf Khalil of the Democratic Union Party told AP the area envisioned for northern Syria would include representation for Turkmen, Arab, and Kurdish populations.
He said that his party is not lobbying for an only-Kurdish region but wants to see the "model of federalism applied to all of Syria."
Idris Nassan, an official in the foreign affairs directorate of Kobani, one of three autonomous areas set up by Kurdish groups two years ago, told Reuters that the areas would be named the Federation of northern Syria.
In Washington, the U.S. State Department said March 16 it would not support the breakup of Syria and that any new federal model would have to emerge from peace talks.
"We've been very clear that we won't recognize any self-rule autonomous zones within Syria," spokesman Mark Toner told reporters.
A representative of the Syrian regime at the peace talks also rejected establishing an autonomous Kurdish federation in Syria, saying the regime's goal is to keep Syria unified.
"What we are talking about here is how to keep the unity of Syria," Bashar al-Jaafari said. "Betting on creating any kind of divisions among the Syrians will be a total failure."
Meanwhile, a leader of an expatriate Syrian group praised Russia's will to support peace talks and expressed hopes the talks would be successful before the U.S. presidential election this fall.
Randa Kassis spoke to reporters after a loosely affiliated, self-described opposition organization known as the Cairo, Moscow and Astana Groups met with the UN special envoy in Geneva.
Kassis noted that "President Obama himself wants the success of these negotiations."
The group is seen as less antagonistic to President Bashar Assad's government than the Western- and Saudi-backed opposition, known as the High Negotiations Committee, that is actively in talks with U.N. special envoy Staffan de Mistura.