Syria conflict: Air strike on Idlib fuel market strains truce
At least 12 people are reported to have been killed in an air strike on an opposition-held town in northern Syria.
Activists said warplanes had bombed a fuel market in Abu Dhuhour in Idlib province, straining a partial truce that began on 27 February.
The attack was described as a "massacre" by the co-ordinator of the opposition High Negotiations Committee.
Riad Hijab said such incidents would inform the HNC's decision on whether to attend peace talks in Geneva.
UN special envoy Staffan de Mistura wants the talks to resume later this week.
Al-Nusra 'threatens protesters'
The Syrian Observatory for Human Rights, a UK-based monitoring group, warned that the death toll from the air strike in Abu Dhuhour was likely to rise.
It added that it was too early to tell if the casualties were civilians or armed combatants because their bodies were burned beyond recognition.
The Local Co-ordination Committees, an opposition activist network, said they were all civilians.
In a conference call with journalists, Mr Hijab condemned what he called "a massacre committed by the air forces of the Russians and the regime".
There was no immediate comment from the government, which has said it is respecting the truce.
But Russia, which has been conducting air strikes against President Bashar al-Assad's opponents since September, said on Monday that it had continued to target the jihadist groups Islamic State (IS) and the al-Qaeda-affiliated al-Nusra Front in line with the agreement on the cessation of hostilities.
Mr Hijab said mainstream rebel groups, some of which are part of an alliance with al-Nusra that controls much of Idlib province, had also been bombed by Russian jets in the past nine days.
The HNC, he added, would consult rebel commanders and other opposition leaders about whether to attend the UN-brokered talks aimed at negotiating a political settlement to the conflict in Syria.
"It will be before the end of this week. There will be a clear decision about this."
Mr Hijab also complained that the government had neither released any detainees nor allowed the flow of aid to besieged opposition-controlled areas to increase in line with the truce deal.
Also on Monday, activists said al-Nusra fighters had broken up a protest against President Assad by opposition supporters in the city of Idlib, threatening to open fire if they did not disperse.
The Syrian Observatory reported that members of al-Nusra and an allied Islamist group, Jund al-Aqsa, had attacked government forced near the village of al-Ais in the neighbouring province of Aleppo.
Meanwhile, the UN's humanitarian co-ordinator in Syria told the BBC that the truce was beginning to make some positive differences in the lives of civilians who were desperately weary of the conflict.
Yacoub El Hillo said a sustained improvement would require commitment from the warring parties.
But he added that it might also take a "popular push" from the Syrian people that would see them declare that they would not accept a return to all-out war.