At least 82 people were killed in Syrian regime air raids Sunday on a town outside Damascus, a monitor said, as the UN's top humanitarian chief held talks with government officials.
The Syrian Observatory for Human Rights, a Britain-based monitoring group, said at least 200 people were also injured in a string of 10 strikes on the rebel-held town of Douma.
Civilians accounted for most of those killed, it said, and the death toll was expected to rise further because many of the wounded were in serious condition.
Observatory director Rami Abdel Rahman said locals had gathered after a first strike hit a market in the town to help evacuate the wounded when the additional raids hit.
At least six raids hit the market, with the others striking nearby in the center of town, Abdel Rahman said.
A video posted online by activists of the aftermath of the attacks showed an intersection strewn with rubble and twisted metal.
The fronts of several buildings nearby appeared to have been sheared off by the force of the blasts, and many cars lay overturned and crumpled.
Warning: Graphic images
Douma lies in the rebel bastion of Eastern Ghouta, a region outside the capital that is the regular target of government air strikes.
Eastern Ghouta has been under government siege for nearly two years, with regime forces tightening the blockade since the start of 2015.
UN aid chief visit
Amnesty International earlier in the week accused the government of committing war crimes in Eastern Ghouta, saying its heavy aerial bombardment of the area was compounding the misery created by the blockade.
The group also accused rebels in the area of war crimes for firing rockets indiscriminately at the capital.
Sunday's strikes on Douma came as new United Nations humanitarian chief Stephen O'Brien held talks with government officials in Damascus on his first trip to Syria since being appointed.
O'Brien, who succeeded Valerie Amos in May, met with Foreign Minister Walid Muallem, state media reported.
Official news agency SANA said O'Brien had expressed willingness to work with the government to alleviate humanitarian suffering in the country.
Close to 12 million people have been uprooted by Syria's conflict, with over four million becoming refugees and another 7.6 million internally displaced.
On Saturday, O'Brien met Syria's deputy foreign minister and visited the central city of Homs, which is now mostly under government control.
"Visited Homs today. Beyond destruction of buildings lies destruction of lives. Syria needs peace," O'Brien wrote on his Twitter account after the visit.
"We are committed to continuing to support humanitarian efforts in Syria. Equal access to all people in need (is) vital for our work," he added.
Fighting after ceasefire crumbles
Elsewhere, fierce fighting raged in rebel-held Zabadani, near Damascus, and rebels rained rockets on two government-held villages in northwestern Syria after the collapse of a ceasefire.
On Saturday, a 72-hour-old truce for Zabadani and the villages of Fuaa and Kafraya collapsed after negotiators failed to reach a long-term deal.
Government forces have been trying for weeks to capture Zabadani, the last rebel bastion in the area along the Lebanese border.
In response, rebels have fired hundreds of missiles at Fuaa and Kafraya, two Shiite-majority villages that are the last regime-held civilian areas in Idlib province.
Meanwhile, a US-trained rebel group said in a statement that Al Qaeda affiliate Al-Nusra Front had freed seven of its members kidnapped two weeks earlier.
"We welcome this noble initiative and urge the brothers of Al-Nusra and hope that they will release in the coming hours the group's commander and other fighters," the statement stamped by the group's command said.
Division 30 is among the units receiving training as part of a US-led program operating from Turkey that is intended to create a force to fight the Islamic State jihadist group.
But after the first 54 members of the force entered Syria in July, Al-Nusra kidnapped 13 of them, including a commander, and at least three more killed in clashes with the jihadist group.
Al-Nusra accused the force of serving US interests.