Bitter fighting blocks international MH17 investigators from site

For a second time, the international team seeking access to the MH17 site thought they had a deal promising safe passage - but it was blown apart.

Escorted initially by separatists, the investigators then rendezvoused with Ukraine government forces now controlling the crash site.

They went in slowly - they came out fast, caught between a diplomatic minefield and a real-life battleground.

For rebels and federal forces, however, the MH17 recovery mission appears to have been sidelined by the government's new offensive.

The Australians, Dutch and the European monitors angry about it. Local families have had to flee to safety, too amid the sound of sirens and the crack of bullets.

Russia's involvement in this conflict is under renewed scrutiny, as the US claims the black patches seen in satellite pictures are scorch marks from missiles fired from Russia into Ukraine's disputed zone.

And Washington says Moscow is still sending arms across the border.

In Kiev, foreign minister Julie Bishop - with Angus Houston - met the Ukraine president after today's crash site turn-around.

"Clearly the situation deteriorated dramatically," she said.

Ms Bishop has been negotiating to allow Australia's security officers to carry weapons. The teams are determined to get back to the wreckage.

But for the moment, all the anguish and courage of the Australian investigators is hitting a brick wall of bitter fighting and political confusion.