A US-led coalition battling the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group says its fighter jets have blocked a convoy of the group's fighters evacuated from Lebanon from reaching eastern Syria, and also struck a number of their comrades travelling from the other direction to meet them.
The attacks on Wednesday were aimed at derailing a deal for ISIL fighters to leave their enclave on the Lebanon border, along with their family members, for areas the armed group holds on Syria's eastern frontier with Iraq.
Iraq's Prime Minister Haider al-Abadi said moving hundreds of fighters towards the Iraqi border was "unacceptable" and "an insult to the Iraqi people", while US officials said ISIL fighters should be killed on the battlefield.
The first set of attacks on Wednesday took place east of Humeima in southeast Syria, said Ryan Dillon, a spokesman for the coalition.
"To prevent the convoy from moving further east, we cratered the road and destroyed a small bridge," he told AFP news agency.
Dillon said the coalition understood there were civilians aboard the buses, and would only bomb the convoy if fighters could be separated from the civilians.
Describing ISIL as a "global threat", he said, "relocating terrorists from one place to another for someone else to deal with is not a lasting solution".
Later, coalition fighter jets also bombed ISIL vehicles heading towards the convoy from the Syrian town of Albukamal.
The buses, which left the Lebanese-Syrian border two days ago, were now stuck in territory held by Syria's government, according to the Syrian Observatory for Human Rights, a UK-based group monitoring the country's conflict via a network of contacts on the ground.
There were about 300 fighters and almost as many family members, including children, on the buses being evacuated, according to Hezbollah, which defended the evacuation deal saying it was the "only way" to find out the fate of nine Lebanese soldiers ISIL had kidnapped in 2014.
The deal also involved ISIL surrendering Hezbollah and Syrian army prisoners and bodies in eastern Syria.
Hezbollah had fought a week-long offensive against ISIL on the Syrian side of the border with Lebanon, coinciding with a simultaneous assault by Lebanese troops on their side of the frontier.
The battles ended on Sunday with the announcement of the evacuation deal.
ISIL is on the back foot in both Syria and Iraq, losing swaths of its territory and its most important towns and cities.
In Syria, the US-led coalition is backing an alliance of Kurdish and Arab armed groups in the north which are assaulting ISIL in the city of Raqqa.
The Russian-backed Syrian army and allied armed groups have meanwhile seized most of the central desert from ISIL, and are advancing eastwards to relieve the army's besieged enclave in Deir Az Zor.
Source: News agencies