GENEVA (Reuters) - The main opposition group at Syrian peace talks in Geneva wants to meet Russian envoys to discuss what it says are Moscow’s broken ceasefire promises, a move diplomats say aims to put pressure on the Russian-backed Syrian government delegation.

Member of the High Negotiations Committee (HNC) Mohamed Alloush of the Jaysh al Islam attends a news conference aside of Syria peace talks in Geneva, Switzerland, April 19, 2016. REUTERS/Denis Balibouse

Russia has sought to revive diplomacy since its air force helped the Syrian army and allied militias defeat rebels in Aleppo in December, President Bashar al-Assad’s biggest victory in six years of war.

Despite the announcement of a ceasefire, a weekend of bombings and air strikes in Syria has rattled the talks that began in Geneva last week.

“The Russians did not fulfil a ceasefire agreement despite the promises from the highest levels of the Russian delegation,” Mohammed Alloush, a negotiator and member of the Jaish al-Islam rebel group, told Reuters.

After a two-hour meeting with U.N. mediator Staffan de Mistura, the head of the opposition delegation Nasr al-Hariri said he had submitted two documents protesting against the grim humanitarian situation and violations of the ceasefire.

Hariri said he believed Moscow was shifting its stance but that he wanted to see constructive support on Tuesday.

He pressed for “practical support that manifests itself in backing for the political process and the demands of the Syrian people by putting pressure on the (Syrian) regime to engage seriously in this process.”

Two diplomats said an eventual meeting was likely to include Russia’s Deputy Foreign Minister Gennady Gatilov and Middle East director Sergei Vershinin.

KEEPING THE TALKS ALIVE

Russia, Turkey and Iran have sponsored parallel talks, in the Kazakh capital Astana, where they reinforced the ceasefire. It paved the way for a resumption of U.N.-led mediations after a 10-month hiatus.

Ahead of Thursday’s opening ceremony, Moscow had called for the government to “silence the skies”, but violence has continued and the warring sides have traded blame while appearing no closer to actual negotiations.

De Mistura said a militant attack in Homs on Saturday was a deliberate attempt to wreck the talks.

“The opposition wants to see the Russians to tell them to put pressure on the government or else this process will lead nowhere,” said a Western diplomat.

He said the Syrian government chief negotiator Bashar al-Ja’afari’s refusal to discuss anything beyond countering terrorism at a weekend meeting with de Mistura was a clear indication that Damascus was not committed.

De Mistura, who is treading carefully to keep the talks alive, has so far talked to the two sides separately as he tries to forge an understanding of how to proceed in future rounds.

He wants to get the two sides to accept an agenda that would be based on Security Council resolution 2254, focusing initially on a new constitution, U.N.-supervised elections and accountable governance.

Russia and the United States were the prime movers behind the last peace talks, which halted as the war heated up. The United States is now taking a diplomatic back seat, leaving Moscow as the main power broker.