The new leader of Ukraine's Crimea region says pro-Russian forces control all access to the strategic peninsula and have blockaded all Ukrainian military bases that have not yet surrendered.

Sergei Aksyonov says riot police and security forces have been joined by 11,000 self-defense troops. All or most of these troops are believed to be Russian, even though the Russian president and defense minister have denied sending in troops.

The West has joined the new Ukrainian leadership in demanding that Russia pull its forces from Crimea, but little progress was reported after a flurry of diplomatic activity Wednesday.

A U.N. special envoy sent to Crimea was threatened by 10 to 15 armed men, a U.N. official said.

Speaking late Wednesday, Aksyonov said his government is in regular contact with Russian officials.