WASHINGTON, July 24 -- U.S. President Barack Obama on Thursday spoke with Australian and Dutch leaders separately over phone on the downing of Malaysian Airlines Flight 17.

In the phone talks with Australian Prime Minister Tony Abbott, the two leaders agreed that a prompt, full, unimpeded and transparent international investigation is an imperative, the White House said.

MH17, a Boeing 777 en route from Amsterdam to Kuala Lumpur, crashed near the eastern Ukrainian city of Donetsk Thursday, killing all 298 people on board.

"They expressed their resolve to push for full, immediate, and secure access for international investigators to the crash site," said a statement issued by the White House.

Obama thanked Abbott for Australia's leadership on this issue, including the country's willingness to send investigators to the crash site as well as federal police if necessary.

In his talks with Dutch Prime Minister Mark Rutte, Obama recalled the moving images seen around the world as the first victims of MH17 returned to the Netherlands and again offered his condolences on behalf of the American people.

Reviewing the current situation on the ground in eastern Ukraine, Obama and Rutte agreed that Russia still has not met the conditions set forth earlier by the leaders of the United States and European Union, according to a separate White House statement.

"Instead of deescalating the situation, they agreed that all evidence indicates Russia is still arming and supplying separatists who continue to engage in deadly acts of aggression against Ukrainian armed forces," said the statement.

Obama and Rutte emphasized that that Russia must not be permitted to destabilize the situation in Ukraine without incurring costs and warned that the international community will need to enact additional sanctions on Russia accordingly, it added.

The West has been claiming that pro-independence insurgents in Ukraine's east shot down the MH17 with a surface-to-air missile, while Russia challenged the allegations, demanding the United States make public its relevant satellite pictures.