An armed group has stormed a police station in Armenia’s capital, Yerevan, taking hostages and calling for the release of political prisoners.
The group released a video demanding opposition leader Jirair Sefilian and a number of others be freed.
It called on Armenians to take to the streets in support.
Mr Sefilian has strongly criticised President Serge Sarkisian and his handling of the conflict in the Nagorno-Karabakh region.
There are reports that several people have been wounded in the Yerevan attack.
The CivilNet identified the group as the Daredevils of Sassoun and said its members had released a video in which they say: “Dear friends, citizens, Armenian nation, it has begun, we are doing this for you… Go out to the streets!”
CivilNet said seven policemen were being held hostage but this has not been independently confirmed. The group was quoted as saying it would retaliate if attacked and had no intention of surrendering.
‘Neutralised’
Armenia’s National Security Service issued a statement accusing the group’s supporters of “spreading misinformation on mass media and social networks about an armed rebellion and about buildings being taken over… the information is not correct.”
It said it was in negotiation with the group at the police station for its surrender.
“This and any other illegal activity will be curbed by the law enforcement agencies and their perpetrators will be neutralised and punished by law,” it said.
Mr Sefilian, a former military commander, has criticised the government’s handling of the long-running conflict involving pro-Armenian separatists in the region of Nagorno-Karabakh.
Nagorno-Karabakh lies within Azerbaijan but has an ethnic Armenian majority. A bloody war erupted after the end of Soviet rule in 1988, and there has been frequent unrest since, the latest in April, when clashes left dozens dead.