PARIS (AFP) - World leaders expressed shock on Thursday after a Malaysian airliner carrying 295 people crashed in eastern Ukraine, calling for an international investigation to determine the cause of the disaster.
President Barack Obama called the crash "a terrible tragedy" and said US officials were trying to establish if any Americans were on board.
"The world is watching reports of a downed passenger jet near the Russia/Ukraine border. And it looks like it may be a terrible tragedy," he said, before going ahead with a previously scheduled event in Delaware.
Obama said his first priority was to determine whether there were any US citizens aboard the crashed jet.
"I have directed my national security team to stay in close contact with the Ukrainian government," Obama said.
"The United States will offer any assistance we can to help determine what happened and why." US Vice-President Joe Biden repeated Washington's offer during a phone call to Ukrainian President Petro Poroshenko, a US official said.
The Kremlin said President Vladimir Putin and Obama - at loggerheads over a new wave of US sanctions over Ukraine - had discussed the crash.
EU foreign policy chief Catherine Ashton called for an international investigation into the disaster.
"Our thoughts are with all those with relatives on board," Ashton said in a statement.
"The circumstances must be clarified without delay and an international investigation needs to shine a light on this tragedy," she added. "We call on all parties in the region to allow full access to the (crash) site."
Malaysian Airlines flight MH17 disappeared from radar screens in eastern Ukraine at around 1415 GMT (10.15pm Singapore time), the carrier said on its Twitter account, hours after the Boeing 777, bound for Kuala Lumpur, had taken off from Amsterdam's Schiphol airport.
Holland's Justice Minister Ivo Opstelten said "there were several Dutch onboard", adding he was "deeply shocked" by the "horrible" images coming from the crash site.
Malaysia's Prime Minister Najib Razak said on Twitter he was "shocked by reports that an MH plane crashed" and announced an "immediate investigation". British Prime Minister David Cameron tweeted: "I'm shocked and saddened by the Malaysian air disaster." He added that government officials were meeting "to establish the facts".
British media have reported that between five and 10 British citizens were on board MH17.
"We are not talking about numbers. Our priority is to find out if Britons involved," a spokesman for the Foreign Office told AFP.
French President Francois Hollande offered "all my solidarity" with relatives of the crash victims, and echoed Ashton's call for a wide-ranging investigation.
Foreign Minister Laurent Fabius said there were "at least" four French people onboard the doomed airliner.
Germany also echoed calls for "an independent international probe".
"We expect everything to be done to shed light on this disaster as quickly as possible," German Foreign Minister Frank-Walter Steinmeier said.