BERLIN - Germany's Angela Merkel challenged Moscow's attempt to pin the downing of a Malaysian airliner on Ukraine, pointing to Russia as a source of separatists' weapons.
But she said it was too soon to talk about retaliatory measures.
The chancellor said there was evidence that the Malaysian Airlines Boeing 777, which crashed into a field in Ukraine killing all 298 people on board, had been shot down.
It needed a ceasefire between Ukrainian government forces and the pro-Russian rebels to permit a full, independent investigation into the tragedy, Merkel said, issuing a "very clear call" for Russian President Vladimir Putin to help make this happen. "These events have once again shown us that what is required is a political solution and above all that it is also Russia that is responsible for what is happening in Ukraine at the moment," Merkel told her pre-summer holiday news conference on Friday.
The incident could mark a pivotal moment in the worst crisis between Russia and the West since the Cold War. Putin put the blame on Kiev for renewing an offensive against rebels two weeks ago after a ceasefire collapsed. He urged an "unbiased" inquiry.
A US official said Washington strongly suspected the plane was downed by a sophisticated surface-to-air missile fired by Ukrainian separatists backed by Moscow. An Italian government source said "there are no doubts" it was shot down by rebels.
Merkel said it should be a top priority to stop the eastern Ukrainian separatists getting weapons from Russia. "It is indeed the case that the separatists are heavily- armed and there are many indications that some of these weapons have come across the border from Russia," she said.
The crash happened a day after European Union leaders stepped up sanctions on Moscow, agreeing to penalise Russian companies that help destabilise Ukraine and to block new loans to Russia through two multilateral lenders.
The EU will draw up by the end of July a first list of companies and people to be hit with asset freezes under the new criteria.