WASHINGTON, July 17 - The United States is prepared to contribute immediate assistance to support a "prompt, full, credible, and unimpeded" international investigation into the Malaysian airliner crash, U.S. President Barack Obama said on Thursday.

In a telephone conversation on Thursday evening, Obama and Dutch Prime Minister Mark Rutte agreed that international investigators should have immediate access to the crash site of the doomed airliner in order to facilitate the recovery of remains and carry out a thorough investigation, the White House said in a statement.

In the talks, Obama expressed his condolences to the people of the Netherlands for the tragic death of Dutch citizens traveling on Malaysia Airlines Flight 17, said the statement.

A Malaysian flight with 283 passengers and 15 crew members on board crashed Thursday in Ukraine near the Russian border. U.S. officials told media that they concluded the plane was shot down by missile.