US and British Ambassadors' "insults" to Moscow during a Security Council open meeting late Wednesday over Crimea prompted their Russian counterpart to threaten not to cooperate with them in the future on other issues such as the Syrian or Iranian nuclear files. "A number of our colleagues spoke up in an excessive way," Russian Ambassador Vitaly Churkin told the Council at the end of the Council meeting. "Madam (US Ambassador Samantha) Power started with a reference to Tolstoy and Chekhov and finished by having let herself down to the level of tabloid journalism. It is simply unacceptable to listen to these insults addressed to our country." "If the USA expects our cooperation in the Security Council on other issues, then Madam Power must understand this quite clearly," he warned. British Ambassador Mark Lyall Grant told the Council that Churkin spoke about the referendum in Crimea held last Sunday being in compliance with international law, without outside interference and through a democratic process. "It is hard to know which of these three assertions is the biggest lie," he wondered. US Ambassador Samantha Power told the Council that "Russia is known for its literary greatness - and what you just heard from the Russian Ambassador showed more imagination than Tolstoy or Chekhov. Russia has decided, it seems, to rewrite its borders, but it cannot rewrite the facts." Churkin told the Council that his country's "historic reunification with Russian Crimea yesterday had been awaited for six decades... A historic injustice has been righted." The Council urgent meeting, called for by France, took place as Secretary-General Ban Ki-moon headed to Russia and Ukraine late Wednesday on a peace mission to de-escalate current tensions. The Council heard briefings on the latest events in the crisis-torn region by Deputy Secretary-General Jan Eliasson and UN Assistant Secretary-General for Human Rights, Ivan Simonovic, who have just returned from Ukraine. Eliasson told the Council that "the crisis has continued to deepen (and) tensions in Crimea and in eastern Ukraine continue to rise ... we are now faced with risks of a dangerous further escalation that could have ramifications for international peace and security and have serious significance for this Council and for the United Nations." Crimean authorities held a referendum last Sunday. Close to 97 percent of those who participated in the referendum voted in favor of secession from Ukraine and joining Russia. Subsequently, Crimea declared its independence, which in turn was recognized by Russia. On Monday, the European Union and the United States moved to apply targeted sanctions against Russian and Crimean officials. On Tuesday, Russian President Vladimir Putin signed a treaty to make Crimea part of the Russian Federation; the Government in Kiev meanwhile has committed to never accept Crimea's independence or annexation, stating that Crimea is an integral part of Ukraine. These events came after months of political unrest in Ukraine led to the removal by Parliament of President Viktor Yanukovych in February, followed by increased tensions in the country's autonomous region of Crimea, where additional Russian military were recently deployed.