German Chancellor Angela Merkel and Foreign Minister Frank-Walter Steinmeier on Thursday called for an independent, international investigation into the downing of a Malaysian airliner over eastern Ukraine.

Ukraine accused "terrorists" - militants fighting to unite eastern Ukraine with Russia - of shooting down the Malaysia Airlines' Boeing 777 as it flew from Amsterdam to Kuala Lumpur with 295 people aboard. Leaders of the rebel Donetsk People's Republic denied any involvement.

Merkel called for an "immediate, independent investigation into the causes of the crash", German government spokesman Steffen Seibert said in a statement.

"For the chancellor, the suspected circumstances in which the plane was allegedly shot down from a great height are shocking", he said.

"If this news is confirmed, she said it would represent a further tragic escalation of the conflict in eastern Ukraine," Seibert added.

In a statement issued after he landed in Mexico City, Steinmeier had earlier said: "The separatists must immediately grant emergency and security services access to the crash site and an independent, international investigation must commence immediately."

"I'm horrified by the news from eastern Ukraine. With hundreds of completely innocent people having died in this terrible way, words fail you."

Asked at a media briefing in Mexico City whether Germany was of the same view as the Ukrainian government on the reasons for the crash, Steinmeier said he could not add anything to the statement.

"I have no information," he said.?