ASTANA (Reuters) - The Syrian armed opposition said on Wednesday it had suspended its participation in peace talks being held in Kazakhstan and demanded an end to government bombing of areas under its control.

A senior official from Kazakhstan’s Foreign Ministry, however, told reporters he expected Syrian opposition figures to return to the talks on Thursday. Another diplomat close to the talks also said the rebels were not walking out completely.

“The delegation has suspended its participation after presenting a memorandum for a total commitment to stopping (government) bombardments,” Ahmad Ramadan, a spokesman for the opposition Syrian National Coalition (SNC), said.

In the memorandum, the rebels demanded “clear implementation procedures” for matters such as enforcing a ceasefire, withdrawal of government forces from areas taken by them since Dec. 30 last year, and release of detainees.

They also again insisted on President Bashar Assad’s departure and objected once again to Iran’s role in the process, describing it as an “aggressor state”. Iran, along with Russia, are Assad’s main supporters against rebels trying to topple him.

In a phone call on Tuesday, U.S. President Donald Trump and Russian President Vladimir Putin sought to defuse tension arising from U.S. air strikes on Syrian government forces in April, expressing a wish for a ceasefire and safe zones for the civil war’s refugees.

ELUSIVE TRUCE

With a ceasefire ever elusive in Syria, the White House said Washington would send a representative to truce talks in the Kazakh capital Astana on Wednesday and Thursday. The State Department said acting Assistant Secretary for Near Eastern Affairs Stuart Jones would attend as an observer.

Aidarbek Tumatov, head of the Asia and Africa department at the Kazakh Foreign Ministry, told reporters the rebels had met the U.S. and U.N. delegations on Wednesday. “Tomorrow, I hope, the (Syrian) opposition will also take part (in the talks).”

U.N. Special Envoy for Syria Staffan de Mistura also voiced hope that the rebels would return to the negotiation table.

“I hope they will because what is important is also to look at the possibility of an outcome on de-escalation,” his office quoted him as saying.

“Every time – every time – we have been having a meeting or a discussion about cessation of hostilities or de-escalation in this case, there have been some incidents produced by one side or the other. The secret is to try to make sure that those incidents stop but also do not kill the opportunity for good news related to that.”

The talks in Astana are sponsored by Russia, Iran and Turkey, which - like the United States - backs the rebel side.

Also on Wednesday, Putin met Turkish President Tayyip Erdogan in the Black Sea resort of Sochi and they reaffirmed their commitment to working together to end Syria’s war. [L8N1I55X6]

Turkish Foreign Minister Mevlut Cavusoglu told reporters on the sidelines of the Sochi meeting that the sponsors of the Astana talks had already agreed three documents and were discussing a fourth.

“On this de-conflicting issue we are having discussions in Astana (which are) very positive and I’m hopeful we will reach an understanding on this as well,” he said.

Russia’s lead negotiator in Astana, Alexander Lavrentyev, said he hoped the sides would sign a memorandum on safe zones on Thursday. He dismissed the rebels’ ultimatum as a bid to put pressure on Moscow, Ankara and Tehran.

“The Syrian opposition must participate in the talks,” he said. “We hope common sense prevails.”