EU leaders held an emergency meeting on Thursday to overcome divisions over how to counter Russia’s takeover of Crimea as pro-Moscow politicians in the autonomous region stoked tension by bringing forward a referendum on its future.

The hastily convened summit in Brussels comes as the US issued a detailed 10-point rebuttal of Russia’s “false narrative” about Ukraine. In addressing Russian claims that it has no troops in Ukraine, that its actions are legitimate and the Ukrainian government is illegitimate, the state department said: “The world has not seen such startling Russian fiction since Dostoyevsky.”

David Cameron, UK prime minister, said on arriving at the summit, that will also include talks with Ukraine’s interim prime minister Arseny Yatseniuk, that there were three points to address: Russia and Ukraine must open talks, the EU must show strong support for the Ukrainian people and a “very clear message” must be sent to Russia that its actions have been “unacceptable and should have consequences”.