By Tom Perry and Suleiman Al-Khalidi

BEIRUT/AMMAN (Reuters) – Thousands of people departed eastern Ghouta for Syrian rebel territory near the Turkish border on Tuesday, the third group to leave under a deal brokered by Russia to surrender the enclave near Damascus to the Syrian government.

Some 7,000 people – most of them fighters and their families – left on 100 buses in the early hours of the morning, to the Syrian Observatory for Human Rights said. More buses drove into eastern Ghouta ahead of a further evacuation.

Rebels have been leaving Ghouta in batches with their families since Thursday, accepting safe passage to the Idlib region in northwestern Syria after they were beaten into retreat in a fierce assault by the Russian-backed Syrian army.

It marks the biggest defeat for the rebellion against President Bashar al-Assad since insurgents were driven from eastern Aleppo in 2016, underscoring his unassailable military position in the seven-year-long conflict.

“We faced two choices: go to Idlib or make peace with the regime,” said Sakhr Yousef, a 24-year-old fighter with the Failaq al-Rahman faction as he was preparing to leave eastern Ghouta with his wife and four young siblings.

“Making peace with the regime is very difficult, making peace with those who bombed us with criminal Russia,” he added in a voice message to Reuters, referring to Assad’s main backer in the conflict.

The rebels being evacuated on Tuesday are leaving from a tract of territory centered around the towns of Arbin, Ain Tarma and Zamalka that was controlled by Failaq al-Rahman rebels.

The last remaining insurgent-held area in Ghouta is the town of Douma. The United Nations said it is highly concerned for 70,000-78,000 people it said were trapped inside.

The Islamist group that controls Douma, Jaish al-Islam, is in talks with Russia that have yet to yield a result.

DISPLACED PEOPLE SUBJECTED TO “SCREENING PROCESS”

Backed by Russia and Iran, the government has repeatedly forced rebels to surrender areas and withdraw to Idlib. The opposition has called this a policy of “demographic change” aimed at forcing dissidents out of Syria’s main cities.

State television, broadcasting from the outskirts of Arbin, showed buses moving along a dusty road through a wasteland of heavily damaged buildings.

A correspondent with Hezbollah’s al-Manar TV said it could take four to five days to evacuate the tens of thousands of people who had agreed to leave Arbin, Ain Tarma and Zamalka.

Hezbollah, a heavily armed Lebanese group backed by Iran, has fought on Assad’s side during the war.

The Russian news agency TASS said 13,190 rebels had left eastern Ghouta in the last three days.

Many tens of thousands of people have fled eastern Ghouta this month into areas controlled by the Syrian government.

The U.N. Office for the Coordination of Humanitarian Affairs (OCHA) said more than 80,000 people had left formerly besieged parts of eastern Ghouta as control shifted since March 9.

The displaced “have to proceed to collective shelters and are not permitted to leave, until they have undergone a screening process and are able to prove a sponsor”, OCHA said in a situation report.

Syrian state TV said the army freed 28 people who had been held captive by militants in Arbin. The Observatory said their release was part of the deal agreed by rebels.

The Syrian military split eastern Ghouta into three separate zones during its assault that began on Feb. 18 and has killed more than 1,600 people, according to the Observatory.

The government says the offensive is securing Damascus from insurgent mortar fire that regularly used to hit the capital including its Old City.

In addition to their foothold in the northwest, anti-Assad rebels still hold a chunk of territory along the southern frontier with Jordan and Israel, and enclaves near Damascus, Homs and Hama.

(Additional reporting Katya Golubkova; Writing by Tom Perry; Editing by Mark Heinrich)