Australian Prime Minister Tony Abbott has described the handling of the MH17 plane crash site as "criminal".

Abbott alleged there has been a "cover-up" concocted to hide crucial evidence about the downing of the Malaysian Airlines plane in Ukraine.

Pro-Russian rebels have been in control of the crash site, where 28 Australians perished in the disaster.

Outspoken leader Abbott said the treatment of the crash site was "not an accident. It's a crime".

He told reporters: "After the crime, comes the cover-up. What we have seen is evidence tampering on an industrial scale and obviously that has to stop."

President Vladimir Putin has faced calls from bereaved families and also politicians around the world to rein in pro-Kremlin militia.

Heavily armed fighters have been filmed picking through wreckage and also accused of even stealing valuables from dead bodies.

But Abbott insisted Putin had been "as good as his word" by approving a UN Security Council resolution which promised air crash investigators access and security.