PARIS (AFP) - The French and Ukrainian presidents said Saturday that any obstruction preventing international investigators reaching the crash site of flight MH17 will "not be tolerated".

Following a phone call with his Ukrainian counterpart Petro Poroshenko, President Francois Hollande said the two had agreed "on the importance of establishing the facts" of what happened to the Malaysian Airlines plane, which crashed in the rebel-held east of Ukraine on Thursday, killing all 298 on board.

"To this end, no obstruction to the work of the international observers from the ICAO (the United Nations' International Civil Aviation Organization) will be tolerated," they said in a statement released by the Elysee palace.

Pro-Russian separatists hindered access to the crash site on Saturday, with international monitors trying to access the scene met by Kalashnikov-wielding militias who allowed them access to only the outskirts of the field.

Rebels backed up by muscular diplomatic support from the Kremlin have shown few signs of being ready to cooperate with an investigation.

Earlier on Saturday, the Dutch PM called on Russian President Vladimir Putin to take action so that bodies from the plane could be removed. "He (Putin) must now take responsibility vis-a-vis the rebels," Prime Minister Mark Rutte told journalists in The Hague.

"Given today's developments and the images from this morning, I sent a message to the president to once more exert his influence on the rebels," he said.

In talks with the German chancellor Angela Merkel, President Putin agreed to an international investigation into the downing of the plane, with an "independent commission" to look into the crash.

US President Barack Obama said Friday that the Amsterdam to Kuala Lumpur flight was shot down by a missile launched from an area controlled by Russian-backed separatists in Ukraine.