International experts started recovery work at the wreckage site of a downed Malaysian airliner in east Ukraine on Friday despite clashes nearby between government forces and pro-Russian rebels.

The group was the largest to reach the site since flight MH17 was shot down over rebel-held territory on July 17, killing all 298 people on board.

Roads had for days been too dangerous to use because of heavy fighting, frustrating efforts to recover all the victims’ remains and push ahead with an investigation.

In the latest clashes, the rebels killed at least 10 Ukrainian paratroopers in an ambush after midnight near Shakhtarsk, one of the closest towns to the wreckage site, the Ukrainian military said.

The rebels said they had pushed back government forces around Shakhtarsk, where fighting has raged for several days. A Ukrainian military official said a further 13 troops were wounded and 11 unaccounted for.

The recovery mission included 70 experts from Australia and the Netherlands, whose countries suffered a big loss of life in the shoot-down, as well as representatives of the Organization for Security and Cooperation in Europe (OSCE).

“Recovery work starts immediately,” the OSCE said on Twitter.

An advance team drove to the site from the nearest big city, Donetsk, on Thursday but only stayed only for about an hour after the sides halted fighting along the route.

Agreement was later reached to extend the limited ceasefire around the route, making it a safe corridor, at talks in Belarus involving Russia, Ukraine, the rebels and the OSCE.

Kiev has accused the rebels of planting mines in the region near the site, suggesting they want to hamper the investigation and hide evidence, but an OSCE official said no evidence had been found to back up the allegations.

Ukrainian officials say about 80 bodies have not been recovered from the wreckage of the Boeing 777. The 298 victims included 193 Dutch and 27 Australians, as well as 43 Malaysians.

The United States says the separatists probably shot down the plane by mistake with a Russian-made missile but the rebels and Moscow deny the accusation and blame the downing on Kiev’s military campaign to quell the uprising.

BESEIGED STRONGHOLDS

In other violence, city authorities said five civilians had been killed and nine wounded in the past 24 hours in Luhansk, which, with, Donetsk, is the last big rebel stronghold.

Government forces have intensified their offensive in mainly Russian-speaking east Ukraine since the airliner came down.

The separatists have been pushed out of other towns they held in the rebellion, mounted against rule by Kiev’s pro-Western leaders and inspired by Russia’s annexation of Crimea after a pro-Moscow president was ousted in Kiev in February.

Luhansk, the smaller of the two main rebel strongholds, is now almost completely surrounded by government troops. It has been cut of from food supplies and left with no electricity or running water, authorities say.

Rebel commander Igor Girkin declared a state of siege in the rebel-held territory in and around Donetsk, saying this allowed his fighters to confiscate cars, construction materials, food, medical equipment and phones.

More than 1,100 people had been killed and nearly 3,500 wounded between mid-April and July 26, the United Nations said.