Poroshenko vows quick end to MH17 probe

Ukrainian President Petro Poroshenko has spoken of the solidarity between his country and Australia and has vowed to expose those responsible for the MH17 tragedy.

Mr Poroshenko pledged to bring the probe into the disaster to a prompt close so the world could know the names of the attackers and has appealed for more support from the West in Ukraine's fight against pro-Russian separatists.

"Those who should be responsible for the terrorist attack ... the world has the right to know their names," he said.

Mr Poroshenko on Friday met Australian officials involved in the investigation into the MH17 disaster.

Speaking at the Lowy Institute in Sydney later in the day, Mr Poroshenko said the "terrorist attack" that occurred almost five months ago demonstrated how close and small the world could be.

"From the very first second of this terrorist attack, we, Ukrainian people, and me as Ukrainian president, were together with the Australians," he said.

Thirty-eight Australians were among the 298 people killed in the July missile attack.

Air Chief Marshal Angus Houston - Australia's lead envoy in the investigation - said there were pieces of wreckage that had been retrieved that would clearly show what happened when MH17 was brought down on July 17.

The first sections of wreckage arrived in the Netherlands earlier this week.

"There's probably some critical pieces of wreckage that will clearly indicate what happened," Air Chief Marshal Houston said after attending Mr Poroshenko's address in Sydney.

But Air Chief Marshall Houston warned the criminal investigation is a much tougher prospect.

"I think it will be a very challenging criminal investigation," he said.

"What I will say is that I know that every lead in the investigation will be pursued and I think that will give us the best chance of finding the perpetrators.

"But there are certain realities and limitations about this that make it exceedingly difficult because of the mere fact that the crash site is in the middle of a war zone."

Mr Poroshenko also thanked Australia for its support in the conflict in Ukraine, appealing for the West to continue its support in combating pro-Russian separatists.

"From all of my heart, I want to thank Australia for the support. I thank you. All of you. For feeling our pain. Please, be with us further on. Together, the whole world can bring peace and stability not only in Ukraine," he said.

"Again, this is not question of Ukrainian or regional security. This is a question of global security."

The comments came after Mr Abbott reaffirmed Australia's support for Ukraine, saying there was "deep solidarity" and that Australia would "do whatever we reasonably can to support Ukraine".

Mr Abbott announced Doug Trappett - who has previously served in Rome, Rangoon and the UAE - would be Australia's first ambassador to strife-torn Ukraine.