Russian President Vladimir Putin was cooperative and constructive when asked for his help in allowing investigators access to the MH17 crash site in Ukraine, Australian Foreign Minister Julie Bishop said Saturday.

Bishop met the Russian leader on the sidelines of the Asia-Europe Meeting, just days after Australian Prime Minister Tony Abbott warned he would confront Putin over the shooting down of the plane at a G20 meet next month.

"I had a very detailed discussion with him," Bishop told the Australian Broadcasting Corporation of their 25-minute talk in Milan.

"I expressed our concerns about the Malaysia Airlines crash, MH17, in which a number of Australians were killed, and I implored him to use Russia's influence over the separatists in eastern Ukraine to enable our investigators to have access to the crash site."

"He said that he would seek to respond to my request by asking the separatists to provide that access."

Bishop said she had told other world leaders that Putin had been "most cooperative and had responded very constructively" to her call.

The Amsterdam-Kuala Lumpur flight was blown out of the air on July 17 as it flew over rebel-held territory in eastern Ukraine, in an attack that Kiev and the West have blamed on pro-Russian separatists operating a Russian surface-to-air missile launcher.

The rebels and Moscow deny responsibility.

On Monday, Abbott vowed to "shirtfront" Putin at next month's G20 summit in Brisbane over the loss of the lives of 38 Australian citizens and residents in the crash.

"I'm going to shirtfront Mr. Putin -- you bet I am," Abbott told reporters, referring to an Australian sporting term in which a player charges someone.

"I'm going to be saying to Mr. Putin -- Australians were murdered and they were murdered by Russian-backed rebels using Russian supplied equipment. We are very unhappy about this."

Three months after the plane was shot down, killing all 298 onboard, debris and belongings lie scattered around the Ukrainian countryside.

International investigators led by Dutch police were forced to suspend their hunt for clues and corpses in August when fighting flared around the site.

Bishop said experts had advised that they required another visit to the crash site to check for any more human remains.

"But also the crash site needs to be accessed by the forensic investigators who are looking into the details of the shooting down of the plane," she said, adding it was an urgent request due to the approach of Europe's winter.

Hundreds of bodies have been sent to the Netherlands for identification from the crash site, but 20 people are still unaccounted for as their remains have not been identified.