(Updates with White House statement, NTSB and FBI available to help, paragraphs 1-3, 6, 13)
By Jeff Mason and Steve Holland
NEW YORK/WASHINGTON, July 17 (Reuters) - The White House called for an immediate ceasefire in Ukraine to allow easy access to a downed Malaysian jetliner and President Barack Obama directed U.S. officials on Thursday to do all they could to support an investigation into what caused the crash.
“It is critical that there be a full, credible, and unimpeded international investigation as quickly as possible,” White House spokesman Josh Earnest said in a statement, urging Russia, pro-Russian separatists and Ukraine to support a cease-fire to permit safe and unfettered access to the wreckage.
The statement came at the end of a day in which Obama went ahead with a trip to tout infrastructure investment in Delaware and to raise money for Democrats in New York despite the incident, in which 298 people were killed.
A Ukrainian official said there were 23 Americans aboard but U.S. officials did not confirm that figure.
Before leaving the White House, Obama spoke by telephone to Russian President Vladimir Putin after the United States on Wednesday imposed the most wide-ranging sanctions yet on Moscow for its actions in Ukraine. During the call, which came at Russia’s request, Putin informed Obama about the downed plane.
Ukraine and Russia traded accusations of blame over the incident. The White House noted that it took place against a backdrop of Russian support for Ukraine rebels.
“While we do not yet have all the facts, we do know that this incident occurred in the context of a crisis in Ukraine that is fueled by Russian support for the separatists, including through arms, materiel, and training,” Earnest said.
“This incident only highlights the urgency with which we continue to urge Russia to immediately take concrete steps to de-escalate the situation in Ukraine.”
Obama made brief remarks about the plane at the beginning of a speech about roads and bridges in Wilmington, Delaware.
“It looks like it may be a terrible tragedy,” he said. “I’ve directed my national security team to stay in close contact with the Ukrainian government. The United States will offer any assistance we can to help determine what happened and why.”
Vice President Joe Biden said it appeared the downing of the jetliner near the Ukraine-Russia border was not an accident and that the passenger jet apparently was “blown out of the sky.”
“This is truly a grave situation,” he said during a speech in Detroit.
Both Obama and Biden spoke by phone with Ukrainian President Petro Poroshenko, offering assistance to help determine what happened to the Boeing 777 that was flying from Amsterdam to Kuala Lumpur, officials said. The White House said the National Transportation Safety Board and the Federal Bureau of Investigation (FBI) were prepared to help.
Obama and his Ukrainian counterpart emphasized that evidence from the crash must remain in Ukraine so international investigators have a chance to look at all of it.
Obama also called Malaysian Prime Minister Najib Razak and Dutch Prime Minister Mark Rutte to express condolences and offer U.S. support for a full probe. The White House said Obama told Rutte that the United States “was prepared to contribute immediate assistance to support a prompt, full, credible and unimpeded international investigation.”
The crash injected an unpredictable element into the increasingly violent confrontation between Ukraine and Russian-backed separatists in eastern Ukraine.
Republican lawmakers, who have called for tough U.S. action against Moscow over Ukraine, called for retaliation against Russia if it were found to have been involved in the crash.
“I believe there should be serious consequences if we find out that it was either Russian agents, Russian equipment or Russians directly that was responsible for the downing of this airliner,” New Hampshire Republican Senator Kelly Ayotte said in a speech in the U.S. Senate.
Obama, determined not to appear to be a hostage of world events, continued with his trip after telling Putin that the United States could impose more sanctions on Russia if Moscow does not take steps to de-escalate the Ukraine crisis.
The new round of U.S. sanctions against Russia included penalties against Russia’s largest oil producer, Rosneft , and other energy, financial and defense firms.
In Wilmington, Obama ate a hamburger with a supporter at a diner after shaking hands and hugging children in the restaurant. In New York, he attended Democratic fundraisers that were not open to the media.
Seeking to show that Obama was on top of the crisis despite his travel, the White House said he convened separate calls with Secretary of State John Kerry and senior members of his national security team, including CIA Director John Brennan, after Air Force One arrived in New York. (Additional reporting by Patricia Zengerle in WASHINGTON; Editing by Paul Tait)