MH17 The White House said yesterday that Russian President Vladimir Putin was "culpable" in the downing of a Malaysian plane over a the war zone in Ukraine and reiterated it was working with the European Union and G7 to impose further sanctions on Moscow.

White House spokesperson Josh Earnest made some of his strongest comments since the plane was shot down, tying the incident to Russia, which the United States has criticised for providing arms to Ukrainian separatists.

"What we also know is that the Malaysia Airlines jet was brought down by a missile that was fired from the ground. It was fired from the ground in an area that was controlled by separatists, and in an area where the Ukrainians themselves were not actually operating anti-aircraft weapons at that time," Earnest told reporters at the White House.

"So that is why we have concluded that Vladimir Putin and the Russians are culpable to this tragedy," he said.

Vice-President Joe Biden spoke to Ukraine President Petro Poroshenko about the investigation into the crash as well as the country's political dynamics yesterday, the White House said separately.

"President Poroshenko underscored that despite the dissolution of the governing coalition in Ukraine's parliament, the government would continue its work to address critical economic reforms," it said in a statement.

"President Poroshenko also informed the vice-president that Russia continued to supply heavy weapons and equipment to the separatists, and that Ukrainian troops were increasingly coming under direct fire from positions on the Russian side of the border," it said.

Biden told Poroshenko the United States was working with the European Union and the G7 on imposing further sanctions on Russia for its "deeply destabilising and irresponsible actions in Ukraine."

- Reuters