The Syrian army and its allies have engaged ISIL fighters in the armed group's last central bastion, a day after taking the heavily defended village of Uqairabat, a monitor reported.

The Britain-based Syrian Observatory for Human Rights, reported on Saturday that the army and its allies had also taken other villages in the area, aided by Russian helicopters.

The Observatory reported that intense fighting continues, but did not give any specific number of casualties.

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The enclave lies close to the main road running, between the cities of Homs and Aleppo near the town of al-Salamiya, and has been the site of intense fighting for months.

Evicting the armed fighters from the area is viewed as necessary to improve security on the road.

The Syrian army, aided by Russian air raids and Iran-backed Shia militias including Lebanon's Hezbollah, had made advances deep into eastern Syria this year against the Islamic State of Iraq and the Levant (ISIL, also known as ISIS).

It is pushing to relieve its besieged enclave in the city of Deir Az Zor, one of the cities on the Euphrates to which ISIL has fallen back after losses in both Syria and Iraq, but has left the pocket in central Syria in its rear.

Late on Friday, a military media unit run by Hezbollah said the army had captured Uqairabat, which it described as ISIL's stronghold in that region.

ISIL convoy standoff

In other parts of Syria, a 17-bus convoy of ISIL fighters and their families continues to be stranded in the Syrian desert, after a US-led coalition blocked its passage from Lebanon to eastern Syria near Iraq.

The coalition issued a statement on Friday saying it has sought an unspecified solution that would save the women and children in the convoy from further suffering.

It said the coalition has not attacked the convoy.

But it said it has struck ISIL fighters and vehicles, including a tank and other armed vehicles, that tried to help the convoy move to the Iraqi border.

The coalition said its officials have contacted Russian counterparts to deliver a message to Syria's government, which had tried to facilitate the convoy's movement earlier this week from western Syria to an area near the Iraqi border.

The movement of the ISIL fighters and their families from Lebanon to the Iraqi border was part of a deal brokered by the Hezbollah and the Syrian army, allowing them safe passage in exchange for the turning over of the bodies of Lebanese soldiers killed.

After the deal was reached, however, the US-led coalition blocked it, leaving the ISIL and their families stranded.