KIEV, April 7 (Reuters) - Pro-Russian protesters who broke into state security headquarters in the eastern Ukrainian city of Luhansk have seized weapons, and highway police have closed down entrances into the city, local police said on Monday.
Mainly Russian-speaking eastern Ukraine has seen a sharp rise in tension since Moscow-backed Ukrainian President Viktor Yanukovich's overthrow in February and the advent of an interim government in Kiev that wants closer ties with Europe.
"Unknown people who are in the building have broken into the building's arsenal and have seized weapons," police said in a statement. Nine people had been injured in the disturbances in Luhansk, they said.
Separately, Interior Minister Arsen Avakov said on his Facebook page that the regional administrative building in the eastern city of Kharkiv, Ukraine's second-largest city, had been cleared of "separatist" protesters.
Pro-Russian protesters in the east seized official buildings in three cities on Sunday, including the regional administrative building in the mining hub of Donetsk.
Demonstrators in Donetsk and Luhansk demanded a referendum be carried out on whether to join Russia like that held in Crimea that paved the way for its annexation by Russia.
Avakov on Sunday accused Russian President Vladimir Putin of orchestrating the "separatist disorder" and promised that disturbances would be brought under control without violence.
The protesters appeared to be responding in part to deposed Yanukovich, who fled to Russia after he was ousted and on March 28 issued a public call for each of Ukraine's regions to hold a referendum on its status inside the country.
Russia has branded the new government in Kiev illegitimate and has annexed Ukraine's Crimea region citing threats to its Russian-speaking majority - a move that has sparked the biggest standoff between Moscow and the West since the end of the Cold War. (Writing by Thomas Grove; Editing by Richard Balmforth and Hugh Lawson)