Australian and Dutch investigators have failed for a third consecutive day to reach the MH17 crash site because of fierce fighting between Ukraine troops and pro- Russian separatists, Australian Prime Minister Tony Abbott said Tuesday.

Abbott, who met with the national security committee of cabinet in Canberra, told reporters it was a "confused situation on the ground".

"There is fighting and it's not just the separatists, it's the Ukrainian government as well," Abbott said.

He said that both sides had made a commitment to using "their best endeavours" to get the site safe enough for the Dutch- Australian team. "And it's high time those commitments were honoured," Abbott said.

Australian Federal Police said the situation was too risky after they encountered shelling on approach to the crash site.

The forensic teams are now caught in the middle of a war surrounding them in the city of Donetsk.

There are still human remains and important forensic information to be retrieved from the area where the Boeing 777 was brought down 11 days ago with the loss of 298 people.