U.N. Secretary-General Ban Ki-moon says he is "gravely concerned about the deterioration of the situation" in Ukraine and plans to speak shortly with Russian President Vladimir Putin.

A Ban spokesman delivered the statement Saturday afternoon as members of the Security Council met in an emergency closed-door session on the rapidly developing events in Ukraine's Crimea region.

Ban's statement calls for "full respect for and preservation of the independence, sovereignty and territorial integrity of Ukraine" and demands "immediate restoration of calm and direct dialogue between all concerned."

Russia's ambassador to the U.N., Vitaly Churkin, told reporters on his way into the meeting, "Busy weekend, isn't it?"

British Ambassador Mark Lyall Grant said the meeting is to determine "what justification Russia claims to have" for its de facto military takeover of the strategic Crimea region.