A letter from Ukraine's U.N. mission circulated during the latest emergency council meeting, where the Ukrainian ambassador again pleaded for international help.
Russia's U.N. ambassador,Vitaly Churkin, told the council that fugitive President Viktor Yanukovych requested Russia's armed forces to establish law and order. Yanukovych fled the former Soviet republic to Russia after his ouster and had said Friday that he would not ask for Russian forces.
Samantha Power, the U.S. ambassador, said: "One might think that Moscow has just become the rapid response arm of the High Commissioner for Human Rights."
Power said the Organization for Security and Cooperation in Europe will begin sending monitors to Ukraine on Monday night
The third emergency Security Council meeting in four days came as the West scrambles to respond to Russia's tightening grip on Crimea amid fears that the Kremlin might carry out more land grabs in pro-Russian eastern Ukraine.
Action by the U.N.'s most powerful body appears unlikely. Russia has veto power as a permanent member and can block the council from adopting any resolution criticizing or sanctioning Moscow.
Churkin told the council he was authorized to read a statement from Yanukovych - and show council members a copy - which says that "as the legitimately elected representative" he believes "Ukraine is on the brink of civil war."
The statement asks President Vladimir Putin to use Russia's armed forces "to establish legitimacy, peace, law and order, stability and defending the people of Ukraine."
Churkin quoted Yanukovych as saying "the life and security and the rights of people, particularly in the southeast part in Crimea, are being threatened" and that there were "open acts of terror and violence."