Fighting rages near MH17 crash site in Ukraine

Fighting between Ukrainian troops and rebels raged Thursday near the crash site of Malaysian flight MH17, as experts in Britain begin analysing crucial data from the downed airliner's black boxes.

A Dutch team leading the probe into the downing of MH17 was stuck in Kiev, unable to join a handful of international investigators at the site, after two warplanes were shot down Wednesday just 45 kilometres from the impact scene in insurgent-held territory.

As the EU prepares to hit Russia with further sanctions over allegations it is arming the separatists accused of downing MH17, dozens more bodies are to be flown to the Netherlands, a day after the first 40 corpses arrived in the grieving nation.

Experts say many remains are still lying in the vast crash site where recovery work has grounded to a halt a week after the disaster, with Dutch authorities saying they can only be sure that 200 corpses have been recovered from the 298 people killed on board.

Australian Prime Minister Tony Abbott said that there was still a need for a rigorous search of the debris zone.

"On the site it is still clear that nothing is happening without the approval of the armed rebels who brought the plane down in the first place," he said.

"There has still not been anything like a thorough professional search of the area where the plane went down, and there can't be while the site is controlled by armed men with vested interest in the outcome of the investigation."

Rebels and government forces have declared a ceasefire in the immediate vicinity of the site, but just beyond, fierce fighting was ongoing.

Ukrainian military said that rockets were being fired "from the Russian side," hitting locations close to Lugansk airport and in several areas in the Donetsk region.

Mortar shells also rained down on Avdiyika in Donetsk region, the army said, without giving details of casualties.

An AFP crew seeking to access one of these combat hotspots Wednesday was turned back by rebels, who fired at their car.

Kiev said the missiles that downed two fighter jets were fired from Russian territory, and that while the pilots ejected safely, there was no information about their whereabouts.

As government troops push on with their offensive to wrest control of east Ukraine's industrial heartland from the pro-Moscow separatists, the Red Cross warned both sides to abide by the Geneva Conventions, declaring that it considered the country to be in a state of civil war.

- EU weighs tighter sanctions -

In Brussels, the EU was looking at punishing Russia, which it accuses of fanning the rebellion in Ukraine's east by arming the separatists.

The bloc said Tuesday it will decide on a list of Russian individuals and entities which it would sanction for providing "material or financial support" to those responsible for the March annexation of Ukraine's Crimea territory and destabilising the east of the country, where MH17 came down.

Putin is staring down fresh European sanctions just a week after the last round was unveiled over Moscow's role in the Ukraine crisis, which has seen East-West tensions spike to their highest point in years.

US intelligence officials have said they believe the rebels mistakenly shot down the doomed Malaysia Airlines flight from Amsterdam to Kuala Lumpur with a surface-to-air missile provided by Russia.

British experts succeeded in downloading the data from the black boxes -- handed over by the rebels following intense international pressure -- and are set to start examining the vital contents.

Kiev said the Netherlands and other countries that lost citizens are proposing to send police to secure the crash site, amid reports by international monitors at the scene that debris has been moved increased fears that evidence was being tampered with.

The arrival of the first bodies from the crash in the Netherlands -- which lost 193 citizens -- on Wednesday brought the grief-stricken nation to a standstill, with a solemn ceremony held at the Eindhoven airport before 1,000 bereaved relatives and members of the Dutch royal family.

Dozens more bodies are due to be flown Thursday to the Netherlands, where they would undergo an identification process that Dutch Prime Minister Mark Rutte warned could take months.

Dutch police have been visiting the bereaved to retrieve DNA samples from items such as hairbrushes, and obtain details of tattoos and fingerprints, as well as consulting medical and dental records to help with the identification.