The armed men took over the police station in Yerevan on Sunday morning, according to the country's National Security Service.

It said the group was "holding hostages under the threat of violence" and that one policeman had been killed and two injured.

Armenian news agencies said that the group was calling for the release of Jirair Sefilian, an opposition leader and former military commander arrested in June for alleged possession of firearms.

Sefilian is an outspoken critic of President Serzh Sarkisian, and has slammed the government's handling of a long-running conflict between pro-Armenian separatists and the breakaway Azeri region of Narorno-Karabakh. He was already jailed for 18 months in 2006 for having issued calls for "a violent overthrow of the government."

'No uprising'

One of the gunmen claimed on Facebook that the hostages included the country's deputy police chief and the deputy police chief of Yerevan.

The security service accused supporters of the hostage-takers of spreading false internet rumors that an armed uprising against the government was underway, with several other buildings seized.

"The National Security Service officially announces that such information is absolutely untrue," it said.

It said negotiations were underway to resolve the situation peacefully. Television reports showed pictures of a heavy police presence at the police station.

tj/jm (AFP, Reuters)