BEIRUT — Syrian and Russian warplanes launched dozens of airstrikes on Syria’s northern province of Idlib on Saturday, a monitoring group said, intensifying pressure on the country’s last rebel stronghold after crisis talks yielded no progress.

At least seven civilians were dead after some 80 airstrikes around the province’s southern edge, according to the Syrian Observatory for Human Rights. It said the violence was the “most intense” in weeks, with helicopters also dropping barrel bombs packed with shrapnel.

Pro-government forces have massed on the edges of Idlib, wedged into Syria’s northwest along the Turkish border. Syrian and Russian officials — key allies in Syria’s long conflict — appear to be preparing for an all-out assault to retake the area.

But there are deep fears that an attempt to reclaim Idlib could touch off major bloodshed and a humanitarian crisis among the area’s 3 million civilians, half of them displaced from elsewhere in Syria.

At a meeting in Tehran on Friday, the presidents of Russia, Iran and Turkey failed to agree on a cease-fire to halt the violence.

Although on different sides of the war, Turkey and Russia share an interest in preventing the situation from unraveling.

Turkey worries the violence could send hundreds of thousands of fleeing civilians to its border. Russia is wary of being drawn deeper into a bloody battle as it tells international partners that Syria is stabilizing and open for reconstruction.

The Observatory said Saturday that some 2,000 people were already on the move from areas being bombed, heading deeper into Idlib province.

Al-Qaida-linked rebels control more than half of Idlib, and much of the Russian and Syrian government rhetoric has focused on defeating the group.

The state-run Al-Ikhbariya TV said Saturday that the Syrian government was retaliating against rebel shelling on a government-held area south of Idlib. The barrage late Friday in Mhradah killed at least nine civilians, according to state media. The reports could not be independently verified.

Separately, clashes broke out in eastern Syria in Qamishli, a town close to the border with Turkey, between government and Kurdish security members. The Observatory said the clashes left 10 government security personnel and seven Kurdish fighters dead.

The town is run by Kurdish-led administrators and forces, but Syrian government troops hold pockets of territory there, including the airport. Occasional clashes erupt there over turf control and authority, reflecting deepening political tension between the uneasy partners.

The U.S.-backed Kurdish administration has been talking with the Syrian government, seeking government recognition of its self-rule areas. But in recent days, Damascus announced that it will be holding local elections, including in Kurdish-ruled areas, undermining the negotiations with the Kurds.

Associated Press contributed.