BEIRUT — The Syrian army captured a key town in the northwest province of Idlib, it said in a statement Wednesday, a significant advance for President Bashar al-Assad's troops, who have repeatedly attempted to retake the town of Maarat al-Numan from rebel factions.

The advance follows a cease-fire struck Jan. 12 by Russia, which backs Assad, and Turkey, which supports various rebel factions in the area. The cessation in hostilities was broken two days later when bombardment resumed, causing displacement in the rebel-held pocket that extends across Idlib province and neighboring Aleppo province.

“There is no going back to Maarat al-Numan this time,” said Bilal Zikra, president of the town’s local council who left the city Monday. “The regime fully besieged the city after I left.”

Zikra said most of the city’s buildings have been destroyed. “There are no people left in the city at all; the regime has spared no shells, rockets or any kind of weapon in targeting it.”

This week, the Syrian army also began advancing westward into the rebel-held countryside around the city of Aleppo. The new front marks a significant escalation and a sign of the Syrian army’s determination to retake the last major rebel bastion.

Photos shared by activist groups show a floods of cars jamming roads as people desperately attempt to escape the onslaught, scrambling northward. But “they are unable to find shelter,” Zikra said. “They are in a miserable and pitiful state.”

Idlib and surrounding areas hold more than 4 million civilians. The recent uptick in violence and attacks has triggered a mass exodus from the area — but civilians have nowhere to go. Most residents hail from other parts of the country and were forcibly displaced there after their own cities and towns were retaken by government troops.

More than 800,000 people are at risk of displacement, the International Rescue Committee said.

Between Jan. 20 and 26, more than 129,000 people were displaced — a number that includes some who have been displaced multiple times — from southern Idlib and the western Aleppo countryside, according to data from the United Nations’ local partners shared with The Washington Post. The United Nations estimates that almost 400,000 have been displaced since Dec. 1, said David Swanson, spokesman for the U.N. Office for the Coordination of Humanitarian Affairs.

Several cease-fires in the area have been organized by Russia and Turkey, and the two countries co-sponsored a de-escalation agreement in 2018 under which Turkey set up observation posts.

As Assad’s troops advanced, the Turkish Defense Ministry warned in a statement Tuesday that it would retaliate “in the strongest manner” against “any attempt to endanger the security” of Turkish observation posts that are dotted throughout the province, including at least three near Syrian forces.

Ankara has expressed alarm at the Syrian offensive, which has sent hundreds of thousands of displaced people fleeing toward the Turkish border. The bloodshed has also fueled demands by Syrians living in Idlib that Turkey do more to protect civilians in the province, including opening up its borders to those trying to flee.

“The regime continues to kill innocent civilians by attacks from both land and air, forcing the civilians to leave their homes and migrate in winter conditions, causing a great human tragedy in Idlib,” the Turkish Defense Ministry’s statement said.

Turkish President Recep Tayyip Erdogan was unusually critical of Russia on Wednesday for the ongoing offensive, suggesting that Moscow was not abiding by previous agreements over Idlib’s future while saying that Turkey had demanded that Russia stop its bombing campaign in the province.

“If you do not stop, then we are running out of patience,” he told reporters on his plane after a visit to Senegal. “We will do whatever it takes from now on,” he added, without being more specific.

Erdogan has generally refrained from criticizing President Vladimir Putin’s government as relations have warmed between Turkey and Russia, including military cooperation and trade ties. But Russia’s backing of the Syrian government offensive has posed a quandary for Turkey, which supports rebel groups in the province and is seeking to prevent hundreds of thousands of refugees from trying to cross the Turkish border.

“If we are going to be loyal partners with Russia, then they must show this. Either they will carry out the process with Syria differently, or they will carry out the process with Turkey differently. There is no other way,” Erdogan said.

Kareem Fahim in Istanbul contributed to this report.