By Louis Charbonneau
UNITED NATIONS Feb 28 (Reuters) - Ukraine's U.N. ambassador on Friday accused Russia of illegally sending military planes and attack helicopters across the border of the former Soviet republic and declared that his country was strong enough to defend itself.
Ambassador Yuriy Sergeyev was speaking to reporters after briefing the U.N. Security Council in a closed-door session on the escalating crisis in Ukraine.
"We are strong enough to defend ourselves," he said outside the council chamber.
Armed men took control of two airports in Ukraine's autonomous Crimea region earlier on Friday in what the country's leadership described as an invasion and occupation by Russian forces. Russia denied involvement in the airport seizures.
U.S. Ambassador Samantha Power, in words that previewed remarks President Barack Obama made later, told reporters that Washington was "gravely disturbed by reports of Russian military deployments into the Crimea."
"The United States calls upon Russia to pull back the military forces that are being built up in the region, to stand down, and to allow the Ukrainian people the opportunity to pursue their own government, create their own destiny and to do so freely without intimidation or fear," she said.
Power, like Sergeyev, declined to characterize Russian military actions when asked if they constituted aggression. She called for an independent international mediation mission to be quickly dispatched to Ukraine.
Russian Ambassador Vitaly Churkin neither confirmed nor denied the specifics of any Russian military movements in the Crimea, but said that any Russian activities there were in keeping with Moscow's existing arrangement with Ukraine on the deployment of military assets there.
"We are acting within the framework of that agreement," he told reporters.
Russia has criticized Ukraine's new government and voiced support for ousted President Viktor Yanukovich, who spoke to reporters from southern Russia on Friday.
Ukraine had asked Lithuania, the president of the Security Council for February, to schedule Friday's meeting of the 15-nation body.
"Due to the deterioration of the situation in the Autonomous Republic of the Crimea, Ukraine, which threatens territorial integrity of Ukraine ... I have the honour to request an urgent meeting of the Security Council in accordance with Articles 34 and 35 of the U.N. Charter," Sergeyev wrote to Lithuanian Ambassador Raimonda Murmokaite.
Article 34 of the U.N. charter talks about the power of the 15-nation council to investigate disputes or "international friction" to determine whether international peace and security is in jeopardy.
The Ukrainian letter to Lithuania's U.N. ambassador came hours after Ukraine's parliament said it would appeal to the council to call a session to consider the problems in the Crimea in the light of an early 1990s understanding in which the big powers agreed to guarantee Ukrainian territorial integrity.
As expected, the council did not take any formal action. Russia is a veto-wielding permanent member of the Security Council and, therefore, able to block any actions proposed by its members.
"During the (council) discussions, support was expressed for Ukraine's unity, territorial integrity and sovereignty," Murmokaite told reporters after the meeting. "The council agreed on the importance of restraint on the part of all political actors in Ukraine and called for inclusive political dialogue."
Sergeyev told reporters there was an "external presence" in Crimea that was "encouraging separatism." He said he had informed the council about "unspecified and armed forces of the Russian Federation on the territory of Ukraine."
"We informed about the illegal crossing (of) the borders by Russian military transport aircraft IL-76, around 10 of them," he said, adding that 11 Russian Mi-24 military attack helicopters had also violated the Russian-Ukrainian border.
British Ambassador Mark Lyall Grant said "the United Kingdom believes that any newly deployed troops that do not answer to the Ukrainian government should withdraw."