Beirut/Geneva: The mainstream Syrian opposition asked the United Nations to halt peace talks on Monday and rebel groups launched a new offensive against government forces, accusing the world body of bias in favour of President Bashar Al Assad.
The opposition's coordinator at the Geneva talks, Riad Hijab, said earlier it was unacceptable for talks to go on if the government and its allies pushed on with sieges and bombing civilian areas, echoing recent criticism of government offensives elsewhere.
Only three delegates met UN envoy Staffan de Mistura for talks on Monday, instead of the usual 15, after a letter signed by unspecified "armed revolutionary factions" said de Mistura and the government were trying to put forward "half-solutions".
"We asked for the postponement of talks, only a postponement until the conditions are right for a resumption of negotiations," Mohammad Al Aboud, a member of the negotiating team, told Reuters.
Another member of the opposition High Negotiations Committee (HNC) confirmed the decision but asked to remain anonymous.
Both sides have accused one another of breaking a February 27 partial truce deal, which does not include IS or Al Qaeda's Nusra Front and which began to unravel as fighting escalated near Syria's second city Aleppo this month.
The cessation of hostilities was meant to provide a breathing space for talks to end the conflict via a political transition for Syria but a second round that began last week has made little headway.
On Monday, rebels launched a fierce attack against government forces in Latakia province, which lies on the Mediterranean coast, and made separate advances further east in Hama, while there were heavy government air strikes in Homs province to the south.
Rebel groups early in the day announced a new battle against the government and its allies which they said was in response to ceasefire violations.
The Latakia and Hama assaults appeared to be that battle, with some of the groups that made the announcement involved in the fighting, the Syrian Observatory for Human Rights monitoring group said. A Syrian military source confirmed intense fighting in the area.
"Today they attacked in the northern Latakia countryside in several areas, in violation of the cessation of hostilities agreement, and also in the northwestern Hama countryside," the military source said.
The Observatory reported that in northern Homs province heavy government air strikes killed four people, and said the death toll was expected to rise, with more people wounded.
Mohamad Al Shamsi, a doctor in the Homs area, told Reuters there had been at least 10 air raids from early morning on Rastan and nearby Deir Foul and Al Houla. Schools had been evacuated and hospitals shut.
Groups including factions fighting under the banner of the Free Syrian Army and powerful Ahrar Al Sham, said in their battle announcement that they would respond "with force" against any government forces that fired on civilians.
They announced the "formation of a joint operations room to begin the battle... in response to violations by the army".
The Geneva talks aim to end a war that has killed more than 250,000 people, created the world's worst refugee crisis, allowed for the rise of the IS group and drew in regional powers. Russia's intervention in the conflict swayed the war in Assad's favour.
A letter signed by unspecified "armed revolutionary factions" urged negotiators to "take firm and decisive stances towards the half-solutions being propagated... by the regime's allies, and de Mistura".
It also said international pledges to deliver aid, halt the bombing of residential areas and free prisoners had not been met. "We follow with great concern and outright rejection the moves of de Mistura, some of which show a total bias towards... the demands of the regime and its allies," the letter said.
In a meeting with the main opposition High Negotiations Committee on Friday, de Mistura mentioned the idea of Assad remaining in power symbolically in exchange for the opposition's nomination of three Syrian vice-presidents.
Diplomats and opposition officials sought to play down the comment, saying it was not de Mistura's idea but rather one of several, from unidentified experts and not considered serious. It was subsequently dismissed outright by the opposition.
But the mere suggestion of Assad staying in power has further distracted from the crux of the talks.
With both sides already trading barbs in Geneva and fighting escalating anew in Syria, the focus appears to be shifting to simply keeping the opposition at the table rather than entering into substantive debate on transition.
"The opposition is split 50:50 on whether to stay or go," said a senior Western diplomat.
"We're telling them that they must not fall into the government's trap because if they walk away, they will be held responsible and it will be difficult to return soon."
The opposition, which is backed by Western powers, says Assad must leave power and cannot be part of any transitional period.
Russia says it is up to the Syrian people to decide on their president.
Assad has rejected the idea of a transitional governing body, saying instead he could broaden the government to include what he described as opposition and independent figures.
On Monday the chief Syrian government negotiator Bashar Ja'afari told reporters he had exchanged ideas with de Mistura on "important issues" but did not take questions or make any mention of a political transition.
"The transitional government will be a difficult task for both the government and the opposition parties," Chinese special envoy Xie Xiaoyan told reporters. "But that doesn't mean they should... leave the discussion and go back to the battleground."