Dominique Faget | AFP | Getty Images

Ukraine accused Russia and pro-Moscow rebels on Saturday of destroying evidence to cover up their guilt in the shooting down of a Malaysian airliner that has intensified a showdown between the Kremlin and Western powers.

As militants kept international monitors away from wreckage and scores of bodies festered for a fourth day on Sunday, Russian President Vladimir Putin urged the rebels to cooperate and insisted that a U.N.-mandated investigation must not leap to conclusions. Moscow denies involvement and has pointed a finger at Kiev's military. The U.N. Security Council was considering a draft resolution to condemn the attack, demand armed groups allow access to the crash site and call on states in the region to cooperate with an international investigation. Australia - which lost 28 citizens - circulated a draft text, seen by Reuters, to the 15-member Security Council late on Saturday and diplomats, speaking on condition of anonymity, said it could be put to a vote as early as Monday.

The Netherlands, whose citizens made up most of the 298 aboard MH17 from Amsterdam en route to Kuala Lumpur, said it was "furious" about the manhandling of corpses strewn for miles over open country and asked Ukraine's president for help to bring "our people" home.

U.S. President Barack Obama said the loss of the Malaysia Airlines flight showed it was time to end the Ukraine conflict and Germany called it Moscow's last chance to cooperate. European powers seemed to swing behind Washington's belief Russia's separatist allies were to blame. That might speed new trade sanctions on Moscow, without waiting for definitive proof. "He has one last chance to show he means to help," Dutch Prime Minister Mark Rutte said after a telephone call to Putin. Britain, which lost 10 citizens, said further sanctions were available for use against Russia. Prime Minister David Cameron, writing in The Sunday Times, said European countries should make their power count. "Yet we sometimes behave as if we need Russia more than Russia needs us."

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German Chancellor Angela Merkel, the most powerful figure in the EU, spoke to Putin on Saturday, urging his cooperation. Merkel's foreign minister, Frank-Walter Steinmeier, told Bild am Sonntag newspaper: "Moscow may have a last chance now to show that it really is seriously interested in a solution." "Now is the moment for everyone to stop and think to themselves what might happen if we don't stop the escalation." Germany, reliant like other EU states on Russian energy and more engaged in Russian trade than the United States, has been reluctant to escalate a confrontation with Moscow that has revived memories of the Cold War. But with military action not seen as an option, economic leverage is a vital instrument. Russian Retaliation Russia said on Saturday it was retaliating against sanctions imposed by the United States last week, before the air disaster, by barring entry to unidentified Americans and warned of a "boomerang effect" on U.S. business. But Foreign Minister Sergei Lavrov and U.S. Secretary of State John Kerry agreed in a phone call to try to get both sides in Ukraine to reach a consensus on peace, Russia's Foreign Ministry said. The U.S. State Department, however, put the onus on Russia, saying Kerry urged Russia to take "immediate and clear actions to reduce tensions in Ukraine". Driving home its assertion that the Boeing 777 was hit by a Russian SA-11 radar-guided missile, Ukraine's Western-backed government said it had "compelling evidence" the battery was not just brought in from Russia but manned by three Russian citizens who had now taken the truck-mounted system back over the border. The prime minister, denying Russian suggestions that Kiev's forces had fired a missile, said only a "very professional" crew could have brought down the speeding jetliner from 33,000 feet (10,000 meters) - not "drunken gorillas" among the ill-trained insurgents who want the Russian-speaking east to be annexed by Moscow. The Wall Street Journal reported that U.S. intelligence assessments indicated that Moscow likely provided rebels with sophisticated anti-aircraft systems in recent days.