The armed opposition to Syrian President Bashar al-Assad said on May 3 it was suspending its participation in peace talks in Kazakhstan's capital, Astana, and calling for an end to government bombardments.
Syrian National Coalition (SNC) spokesman Ahmad Ramadan made a one-sentence statement on the first day of a May 3-4 round of the negotiations process sponsored by Russia, Turkey, and Iran.
"The delegation has suspended its participation after presenting a memorandum for a total commitment to stopping [government] bombardments," Ramadan said.
Ramadan said the opposition delegation would remain in Astana to discuss violations of a cease-fire brokered in December by Russia, Iran, and Turkey, and to present its questions about a Russian proposal for safe zones.
The United Nations envoy to the talks, Staffan de Mistura, and the Russian envoy, Aleksandr Lavrentyev, issued statements urging the opposition delegation to rejoin the discussions on May 4.
The Russian plan was discussed by Russian President Vladimir Putin and Turkish President Recep Tayyip Erdogan in Sochi earlier on May 3.
Lavrentyev said it envisions the establishment of four zones in which the armed opposition, "backed by the guarantor countries, would be directly combating terrorist organization groups."
Lavrentyev said the plan "should break a stalemate in the problem of separating moderate opposition from terrorist organizations…and will help substantively lower the level of armed confrontation between the Syrian armed opposition and government troops."
He added that he could not elaborate further because the plan was still under negotiation. He said he hoped a memorandum on the plan would be adopted on May 4.
Ramadan told the Associated Press that the opposition could not accept the safe-zones proposal in the form that it was presented on May 3.
U.S. President Donald Trump and Russian President Vladimir Putin discussed safe zones in a telephone conversation on May 2 that focused on Syria, according to the White House and the Kremlin.
'Very Good' Conversation
A White House statement said Trump and Putin "agreed that the suffering in Syria has gone on for far too long and that all parties must do all they can to end the violence."
"The conversation was a very good one, and included the discussion of safe, or de-escalation, zones to achieve lasting peace for humanitarian and many other reasons," it said, without going into detail.
Russia and Iran have supported Assad throughout the Syrian civil war, which began with a violent government crackdown on protests in 2011, while Turkey and the United States have backed his opponents.
The United States also leads a coalition conducting air strikes and other operations against Islamic State (IS) militants in Syria.
Russia says it is also battling IS in Syria, but Western officials say the Russian military operations have mainly targeted Assad's opponents.
The United States has mainly backed a separate UN-sponsored peace process in Geneva. But after Trump's phone conversation with Putin, the White House said Washington would send a representative to the talks in Astana.
The U.S. State Department said acting Assistant Secretary for Near Eastern Affairs Stuart Jones would be attending as an observer.
The war in Syria has killed an estimated 400,000 people and prompted millions to flee their homes, adding to an influx of refugees into countries in the Middle East, Europe, and elsewhere.