Armenian Prime Minister Nikol Pashinyan has warned of an “attempted military coup”, after the nation’s armed forces asked him and his cabinet to resign.
The army “must obey the people and elected authorities,” he told thousands of supporters in the capital Yerevan.
“The army is not a political institution and attempts to involve it in political processes are unacceptable,” he told his supporters gathered on Republic Square.
Later on Thursday Mr Pashinyan sacked armed forces chief Onik Gasparyan and his deputy, Tiran Khacharyan.
He invited the opposition to hold talks on how to resolve the crisis, stressing that any change in power must take place “only through elections”.
Meanwhile, opposition supporters staged a rival demonstration in the capital, insisting that Mr Pashinyan must go.
Vazgen Manukyan, one of the opposition leaders, urged the crowds to start blocking the parliament, saying lawmakers should be brought in to vote for Mr Pashinyan’s dismissal.
Mr Pashinyan has faced mass protests after losing last year’s conflict with Azerbaijan over Nagorno-Karabakh.
Nagorno-Karabakh is internationally recognised as part of Azerbaijan but has been under control of ethnic Armenians since a 1994 truce.
During the bloody six-weeks of fighting late last year, Azerbaijan not only recaptured areas around the enclave but also took the key town of Shusha inside it.
Currently hundreds of Russian peacekeepers are deployed manning the disputed territory.
Mr Pashinyan, 42, a former journalist, took office after leading a peaceful 2018 revolution in the post-Soviet state.