(Adds more than 50 people leaving building)
By Thomas Grove
LUHANSK, Ukraine, April 9 (Reuters) - More than 50 people left a state security service building overnight that had been seized by pro-Russia activists in eastern Ukraine, following negotiations between protesters and officials, Ukraine's state security service (SBU) said early on Wednesday.
The SBU said on Tuesday that the protesters who seized the local headquarters of state security in Luhansk on Sunday had wired it with explosives and were holding 60 people hostage, though this was denied by the protesters themselves.
After negotiations overnight, 51 people left the building without weapons, the SBU in the Ukrainian capital Kiev said. It was unclear if they were protesters or hostages.
Interfax Ukraine news agency later put this number at 56 and said negotiations were continuing between the protesters and local officials to end the occupation.
The activists denied on Tuesday they had any explosives or were holding hostages. But they conceded they had seized an armoury full of automatic rifles.
"We do not need hostages to get what we want," said Anton, who declined to give his second name.
The Luhansk building was one of several seized by protesters in the east of the country demanding regional referendums on independence from Kiev.
Protesters in Donetsk, to the south, remain in control of the main regional authority building, but authorities ended the occupation in the city of Kharkiv.
The Ukrainian government says the occupations are part of a Russian-led plan to dismember the country.
U.S. Secretary of State John Kerry accused Russian agents and special forces on Tuesday of stirring separatist unrest and said Moscow could be trying to prepare for military action as it had in Crimea, annexed by Russia last month. (Writing by Richard Balmforth; Editing by Ron Popeski)