The fourth phase of the exodus of Syrian rebels and their families was set to get under way on Saturday in Al Waer, the last opposition-held district in Homs, with some 2,500 people expected to leave.

Evacuations of the rebel enclave are part of a deal with the government brokered by Russia - but opposition activists have called it forced displacement.

The evacuees are being moved to Jarablus in Aleppo province, but many others who have left Al Waer

have gone to Idlib province, where a suspected chemical attack that killed scores of people took place earlier this week.

READ MORE: Rebels leave Al Waer district under evacuation deal

Al Jazeera's Mohammed Jamjoom, reporting from Reyhanli on Turkey's border with Syria, said that 55 buses carrying around 2,500 evacuees were expected to leave the enclave in this latest round - but that many were unhappy with the terms of the evacuation.

"These are people that have not accepted the terms of the national reconciliation movement," said Jamjoom.

"They say that these terms are being imposed on them by the Syrian regime, by the Russians, by their Iranian allies as well."

Jamjoom reported that many of the evacuees say they have no other choice but to leave.

"They are quite concerned about what is going to happen to them going forward."

The evacuation, overseen by Russian and Syrian forces, is the fourth phase of an agreement reached last year that saw hundreds of fighters and their families leave the area.

The Syrian government has increasingly tried to press besieged rebel areas to surrender and accept what it calls reconciliation agreements that involve fighters departing for northern Syria.

Damascus describes such deals as a good way of bringing the country closer to peace after more than six years of conflict. But the opposition describes them as a tactic of forcibly displacing people who oppose Syrian President Bashar al-Assad after years of bombardment and siege.

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"There is a deliberate strategy from the Syrian government in terms of retaking some of these areas is that they lay a siege on the area preventing all kinds of supplies from getting in, including food, medical supplies etc and then they indiscriminately attack these areas," the deputy director of emergencies at Human Rights Watch, Ole Solvang, told Al Jazeera last month.

Once completed, it would mark the biggest evacuation during the war out of one Syrian district, which is home to about 40,000 civilians and more than 2,500 fighters, the British-based Syrian Observatory for Human Rights (SOHR) said last month.

Elsewhere in Syria, Syrian opposition activists said fighter jets on Saturday struck the rebel-held town of Khan Sheikhoun where a suspected chemical attack killed more than 80 people, including many children, on Tuesday.

According to the UK-based Syrian Observatory for Human Rights, one woman was killed in the air raid on the eastern side of Khan Sheikhoun.

On Friday, the US launched fired nearly 60 Tomahawk missiles at an airbase in Syria which it believes was used by Syrian government forces as a launchpad for the alleged chemical attack on Khan Sheikhoun.