WASHINGTON: The US-led coalition has killed dozens of jihadists linked to a convoy of Daesh buses from Lebanon stranded in the middle of the Syrian desert, a U.S. military official said Thursday.

The convoy, which initially consisted of 17 vehicles, has been stalled in the Deir Ezzor region since August 29.

U.S. officials say about 300 Daesh jihadists were initially aboard, along with a similar number of civilians, likely family members.

The fighters had been headed from Lebanon to a Syrian town near the Iraq border as part of an evacuation deal negotiated between Daesh and Hezbollah, which has intervened in the war in neighboring Syria to prop up the Damascus government.

The evacuation agreement ended separate near 10-day offensives against Daesh by Hezbollah and the Syrian army in Syrian western Qalamoun and by the Lebanese Army from near Ras Baalbeck and Al-Qaa in Lebanon. The militants had been entrenched in the mountainous border areas since 2014 when they were pushed out of the nearby town of Arsal that was briefly overun by Daesh and Jabhat Fatashal-Sham - previously known as the Nusra Front.

The United States was not party to the deal and previously acted to block the convoy just short of the border by bombing the road and a bridge leading from the Syrian town of Hmaymah to the Daesh-held town of Albukamal further east.

Colonel Ryan Dillon, a U.S. military spokesman, said the coalition has not targeted the convoy itself and was permitting food and supplies to reach the stranded vehicles, but he noted about 85 Daesh fighters either from the convoy or heading by vehicle to link up with it had been picked off.

"We have struck individual Daesh fighters, and fighters that leave in small groups to walk away," Dillon told Pentagon reporters in a phone briefing from Baghdad.

"As soon as they get far enough away from the buses, we have and will continue to strike Daesh fighters ... where we can hit them without causing harm to the civilians that are part of that convoy."

The 17-vehicle convoy split in two last week, with six buses heading west toward the Palmyra region, which is under Syrian regime control.

"Those buses drove further into western Syria, we just made the decision to stop monitoring it as they drew further into the interior," Dillon said.

The coalition has offered to try to bring the situation to a head by contacting Russia and offering a proposal that would allow the civilians to escape.

Dillon said that proposal had not gained any traction, leaving open the question of the fate of the Daesh fighters and the civilians.

"We don't see it as our issue," he said.

The deal to allow the militants to leave the Lebanese border areas has met international criticism as well as local condemnation. Several Lebanese officials have criticised the deal which they say undermines the authority of the state.

The move was also condemned by Hussein Youssef, the unofficial spokesman for the families of nine missing solders taken hostage and later killed by the Daesh militants. He said he Wednesday that he would have preferred never to find the bodies of the soldiers than to have done so in a deal brokered by Hezbollah.