Most of an ISIL evacuation convoy stuck in east Syria has crossed out of government territory headed to ISIL-held Deir Az Zor province and is no longer the responsibility of the Syrian government or its ally Hezbollah, according to the Lebanese armed group.

Hezbollah said in a statement on Saturday that out of 17 buses full of hundreds of lightly armed ISIL fighters and their families only six remained in government-held territory under the protection of the Syrian state and Hezbollah.

The buses, which left ISIL's enclave near Syria's border with Lebanon on Monday, were in danger from US-led coalition air raids before reaching their destination of Deir Az Zor's Al-Bukamal city, near the Iraqi border.

"The Syrian state and Hezbollah have fulfilled their obligations to transfer buses out of the area of Syrian government control without exposing them," Hezbollah's statement said.

Rami Abdurrahman, head of the UK-based Syrian Observatory for Human Rights, said dozens of fighters and civilians left the buses and drove into ISIL-held parts of Deir Az Zor in 12 civilian vehicles.

Omar Abu Laila, a member of the DeirEzzor 24 activist group, who currently lives in Europe, gave an account similar to that of Abdurrahman.

Remaining buses

Hezbollah said there were old people, casualties, and pregnant women in the remaining six buses stranded outside Syrian government control in the desert and called on the international community to step in to prevent them coming to harm.

"The so-called international community and international institutions should intervene to prevent the occurrence of an ugly massacre," said the statement.

The US-led coalition vowed to continue monitoring the convoy and disrupt any effort it makes to cross into ISIL territory, but said it would not bomb it directly because it contains civilian family members of the fighters.

On Wednesday, the coalition said its jets cratered a road and destroyed a bridge to stop the convoy progressing, and bombed ISIL comrades coming the other way to meet it.

READ MORE: US-led air attacks block ISIL evacuation deal

A commander in the pro-Assad military alliance said earlier on Saturday that Hezbollah and the Syrian army changed the route of the convoy from Humeima, a hamlet deep in the southeast desert, to a location further north, but coalition jets again struck near that route.

On Friday, coalition jets made mock air raids over the convoy, the commander added.

"It caused panic among the Daeshis. The militants are scared the convoy will be bombarded as soon as it enters Deir Az Zor," the commander said, using a plural form of the Arabic acronym for ISIL to refer to its fighters.

Insult to the Iraqi people

Iraqi Prime Minister Haider al-Abadi has described the evacuation deal between ISIL and the Syrian government brokered by Hezbollah as "unacceptable" and an "insult to the Iraqi people".

In Lebanon, some criticised it for allowing fighters suspected of killing Lebanese citizens to escape on "airconditioned buses".

Deir Az Zor in Syria's east is one of ISIL's last remaining strongholds, where it holds most of the province and parts of its capital of the same name.