BEIRUT: Turkish troops and allied opposition fighters have begun a siege of the Syrian Kurdish-held northern town of Afrin, the Turkish military said Tuesday.

The military said in a brief statement that the siege of Afrin, the main town in the enclave of the same name, had begun Monday. It said the military had taken control of “critical areas” of the town but did not provide details. Thousands of people had started to flee Afrin on Monday as the Turkish troops got closer to the town, heading toward nearby government-controlled areas. Turkey launched a military offensive into the border enclave on Jan. 20 to drive out Syrian Kurdish forces that it considers to be “terrorists” and an extension of Kurdish rebels fighting inside Turkey. The violence in northern Syria came as the largest rebel group in the besieged suburbs of the Syrian capital Damascus vowed not to leave the area and to continue fighting advancing government forces as opposition activists reported a new wave of bombardment Tuesday morning that inflicted casualties. The Army of Islam statement came hours after it said it had reached an agreement with government-allied Russian forces to evacuate the wounded from the enclave. Its statement said the deal with the Russians was reached through the United Nations. The Britain-based Syrian Observatory for Human Rights said Tuesday that the evacuations are expected to begin “within hours” under UN supervision. Syrian TV showed some people arriving at the Wafideen crossing after they left the area with a woman saying that she has been waiting for more than a year to evacuate her sick child. The TV also showed an older man being carried while on a wheel chair before boarding an ambulance. Another woman was held as she could hardly walk. The Army of Islam statement late Monday was responding to some local reports that said it is negotiating with the Syrian government and its Russian backers to leave the area known as eastern Ghouta. Syrian government forces captured more than half of eastern Ghouta over the past two weeks and laid a siege on the group’s stronghold of Douma. Eastern Ghouta is home to some 400,000 people who are living amid harsh condition because of bombardment and lack of food resulting from a monthslong government siege. Opposition activists say that since the latest wave of bombings and ground offensive began, more than 1,100 civilians have been killed in eastern Ghouta. Hamza Bayraqdar, Army of Islam’s chief military spokesman, said in a video statement posted online that “our revolutionary ideology does not allow us to sell the blood of the holy warriors who liberated Ghouta.” He added that “we will stay in our Ghouta to defend it until we achieve one of two good things,” he said using an Islamic term that means either “victory or martyrdom.” The Observatory and the opposition’s Syrian Civil Defense, reported a wave of airstrikes and shelling Tuesday morning on the towns of Saqba, Jisreen, and Kfar Batna killing and wounding two dozen people. The Observatory reported that evacuations of insurgents and their families began from another rebel-held pocket south of Damascus. It said hundreds of fighters and their families began leaving on board of buses from the neighborhood of Qadam toward the rebel-held province of Idlib in the country’s northwest. It said the government reached an agreement with rebels in Qadam to evacuate the area recently. The move appears to have angered the Islamic State group that controls two areas adjacent to Qadam. IS attacked areas evacuated by the rebels and handed over to Syrian troops, the Observatory said. IS issued a statement saying that its fighters attacked Syrian army positions in Qadam inflicting casualties among the troops. IS said it attacked troops in positions they took from rebels.