Tens of thousands of people took to the streets of Yerevan on Thursday to protest against Prime Minister Nikol Pashinyan and demand he step down.
They are angry at the Armenian government's further territorial concessions to neighbouring Azerbaijan after the loss of the war over disputed region of Nagorno-Karabakh.
The demonstrators, led by the Archbishop of Tavush, Bagrat Galstanyan, demanded Pashinyan's resignation, a dpa reporter at the scene saw.
Galstanyan initially called on Pashinyan to resign within an hour, but the ultimatum went unanswered, so he vowed to take further measures.
The demonstrators are planning to spend the night in the central Republic Square in Yerevan.
A vote of no confidence against Pashinyan is being negotiated with three parliamentary groups, the archbishop said, though it was unclear how many members of the ruling Civil Contract party will oppose Pashinyan. Civil Contract has an absolute majority in parliament.
Pashinyan has faced strong and growing pressure due to the conflict with Azerbaijan.
The former Soviet republics of Armenia and Azerbaijan have long fought over the mountainous region of Nagorno-Karabakh, which has a mostly Christian Armenian population, but comprises about 4,500 square kilometres within predominantly Muslim Azerbaijan. It is internationally recognized as part of Azerbaijan.
After the collapse of the Soviet Union and the flare-up of ethnic conflicts, it seceded from Baku in 1994 with the help of Yerevan.
Azerbaijan recaptured part of these territories in 2020. In the fall of 2020, Russia then deployed troops to the crisis region based on an agreement between Armenia and Azerbaijan and a ceasefire, to act as a buffer and prevent further fighting.
However, the Russian soldiers did not intervene in Azerbaijan's attack on Nagorno-Karabakh in 2023. The leadership of the separatist region was forced to surrender after a short period of fierce fighting. More than 100,000 ethnic Armenians then fled the region.
Azerbaijan now has complete control of Nagorno-Karabakh.
Border disputes continue between the two countries and Azerbaijan, backed by Turkey, is claiming further territory from Armenia, its weaker neighbour.
Pashinyan recently signalled he would make concessions in order to seal a peace treaty, earning fierce resistance from Armenians.