U.K. Prime Minister David Cameron called for Europe to ratchet up sanctions against Russia, if it is proved the Malaysia Airlines MH17 plane was downed by separatists rebels in Ukraine using weapons from Moscow.
Speaking in the British Parliament on Monday, Cameron said evidence strongly indicated that the civilian plane was shot down by accident by pro-Russian separatists. The passenger jet crashed on Thursday with 298 people on board, who all died.
Read More Russia sanctions may get 'much worse' after crash
He advocated the European Union initiate sanctions against "cronies and oligarchs" associated with President Vladimir Putin, even if they played no direct role in destabilizing Ukraine.
Cameron said EU should also look to instigate tougher "tier three" sanctions against Russia, which would cripple whole sectors of the country's economy.
—By CNBC's Katy Barnato