Vitaly Churkin showed a copy of the letter to the members of the UN Security Council as he spoke at an open council meeting on the current crisis in Ukraine.
"People are persecuted on political and language grounds," the Russian permanent representative to the UN quoted the letter, which was dated March 1, as saying.
"In this context, I appeal to the president of Russia, Vladimir Putin, to use the armed forces of the Russian Federation to re-establish the rule of law, peace, order, stability and to protect the people of Ukraine," he continued.
Moscow, said the envoy, still recognizes Yanukovych, who was removed from power by the Ukrainian parliament last month, as Ukraine's legitimate leader, rather than interim President Oleksandr Turchynov.
Churkin also criticized some Western UN ambassadors for getting information about Ukraine only "from US TV."
Reading the letter to reporters after the council meeting, Churkin said Ukraine has plunged into "chaos and anarchy" and "is in the grip of outright terror and violence driven by the West".
Ukraine's UN ambassador, Yuriy Sergeyev, accused Russia of "an act of aggression", telling the Security Council that Russia has deployed some 16,000 troops from Russian territory to Crimea since February 24.
Crimea, a multiethnic region with a large Russian population, enjoys a high degree of autonomy after Ukraine gained independence from the Soviet union in August 1991. Russia has maintained its only Black Sea naval base in the port of Sevastopol, Crimea.
