Evidence has been tampered with on an "industrial scale" at the crash site of Malaysia Airlines Flight MH17, Australian Prime Minister Tony Abbott said Tuesday, calling it "a cover-up".

Abbott, whose government was behind a U.N. Security Council resolution that Monday unanimously demanded full access to the site in rebel-held east Ukraine, admitted progress had been made but said more needed to be done.

With the backing of Russia, the U.N. Security Council on Monday unanimously adopted a resolution condemning the downing of a Malaysian passenger jet and demanding crash site access in rebel-held east Ukraine.

Australia took the lead in drafting the resolution that was adopted after some changes were made to satisfy Moscow.

Russia on Monday called for a ceasefire between Israel and Hamas and for the international community to urgently take concerted action to stop the suffering of civilians on both sides.

"The new dangerous cycle of violence has shown with absolute clarity the need for a ceasefire," the Russian foreign ministry said in a statement as the United States and the United Nations demanded an immediate ceasefire.

U.S. President Barack Obama voiced outrage Monday that the probe into the downing of a Malaysian airliner was being hampered by Ukrainian rebels and demanded Russian leader Vladimir Putin force them to cooperate.

"The Russian-backed separatists continue to block the investigation. They've repeatedly prevented international investigators from gaining full access to the wreckage. As investigators approached they fired weapons into the air... All of which begs the question what exactly are they trying to hide?" Obama asked angrily in a statement on the White House south lawn.

Canada's prime minister announced Monday further economic sanctions against Russian entities and individuals, saying the downing of flight MH17 was a "direct product of Russia's military aggression and illegal occupation" of Ukraine.

"The outrageous and criminal act of shooting down a civilian airliner last week is a direct product of Russia's military aggression and illegal occupation of Ukraine, and demonstrates the need for the international community to continue applying pressure on the Putin regime," Prime Minister Stephen Harper said in a statement.

Germany's foreign minister said Monday the EU will "raise the pressure" on Russia over the Ukraine crisis following the downing of Malaysian flight MH17 with a suspected missile.

Frank-Walter Steinmeier said "the terrible deaths of hundreds of innocent people in the plane crash a few days ago, the ghastly images of the crash site and the ruthless behaviour of the separatists have rightly caused outrage and shock around the world".

A bereaved Dutch father has written a savagely ironic open letter to whoever shot down flight MH17, "thanking" them for killing his 17-year-old daughter Elsemiek, "my dear and only child".

"Thank you very much Mr (Russian President Vladimir) Putin, separatist leaders or the Ukrainian government, for murdering my dear and only child," Hans de Borst said in the letter published by Dutch media on Monday.

Britain will push for EU sanctions targeting whole sectors of the Russian economy in the wake of the Ukraine plane disaster even if it means taking a short-term "hit" to the economy, its ministers said on Monday.

Deputy Prime Minister Nick Clegg said "the time has now come for sanctions to be tightened further", and stressed that inaction so far over the Ukraine crisis had "not served us well".

Russia on Monday said its flight records show a Ukrainian fighter jet was flying close to the Malaysian passenger airliner just before it crashed and that Kiev was operating radar stations used for missile systems.

Moscow also denied supplying Ukrainian separatists with Buk missile systems or any other weapons, as it sought to head off international accusations it was responsible for the downing of the Malaysian plane with 298 people on board.

The Syrian regime believes its "victory" over the rebellion is assured, thanks to Moscow and its other allies' support, Foreign Minister Walid Muallem said in a letter to his Russian counterpart Sergei Lavrov.

"Syria's unwavering confidence in its victory is thanks to its people's resistance, and to the support of its friends, especially Russia," said Muallem in his letter, sent to mark the 70th anniversary of the opening of diplomatic relations between the two countries.