BEIRUT (AP) — Under an agreement between the warring sides in Syria, hundreds of rebels and their families began boarding buses on Monday to leave a besieged opposition-held neighborhood of the capital, Damascus, for rebel-held areas in the country's north, according to state TV and opposition activists

The development is the latest in a series of population transfers in the war-torn country over the past year. However, the evacuation of some 1,500 people from Damascus' northeastern Barzeh neighborhood is the first in this area.

It's also the first since Russia, Turkey, and Iran agreed last Friday to enforce a cease-fire between government and opposition forces in four areas in Syria.

Barzeh came under siege last month, after government forces captured a major road near the area separating it from rebel-held eastern suburbs of Damascus.

Over the past months, tens of thousands of people living in besieged areas around Damascus, Homs, and Aleppo — Syria's largest city — have surrendered after prolonged sieges in exchange for safe relocation to opposition-held areas elsewhere in the country.

The Britain-based Syrian Observatory for Human Rights said hundreds are expected to leave Barzeh, with around 1,500 expected to leave on Monday and more in the coming weeks.

Mazen al-Shami, an opposition activist based near Damascus, said the opposition fighters and their families are boarding the buses in Barzeh to head to the rebel-held northwestern province of Idlib. He posted a photo online showing fighters with their automatic rifles standing near buses.

The government-controlled Syrian Central Military Media said some 500 fighters will head to Idlib, while dozens of other Barzeh residents plan to stay, apparently benefiting from an amnesty offered to opposition fighters who decided to return to normal civilian lives.

Syrian state TV said some 60 buses and ambulances of the Syrian Arab Red Crescent were in Barzeh for the evacuations.

Some opposition activists have criticized the population movements as "forced displacement."

Last month, U.N. Secretary-General Antonio Guterres warned that the forced movement of civilians could constitute a war crime. He said the U.N. has repeatedly expressed concern at local evacuation agreements that follow the decimation of an area and result in forced displacement of civilians.

The U.N. chief reminded Syria's government and opposition groups that forced displacement of civilians is "permissible solely in order to guarantee their security or for imperative military necessity." Otherwise, forced movements are prohibited and may be war crimes, he said.

As for the Russia-Iran-Turkey cease-fire deal, there are still questions about how it will be enforced. Russia and Iran, which support the government, and Turkey, which backs the rebels, may deploy armed forces to secure the four so-called "de-escalation zones," in what would amount to unprecedented coordination between the three countries.

Even if the agreement is enforced, it is unlikely to end the conflict. Despite several rounds of U.N.-mediated negotiations in Geneva, the government and opposition remain at odds over President Bashar Assad's future role in Syria.

The United States is not party to the de-escalation agreement, and the Syrian government and opposition have not signed on to the deal. The armed opposition is critical of the agreement and has demanded a national cease-fire instead.