Several thousand protesters took to the streets of the Armenian capital on Wednesday morning after talks between the opposition and the acting prime minister were called off.
Armenian police began gathering in the centre of Yerevan on Wednesday after a protest against the country's ruling elite erupted there, witnesses said.
Nikol Pashinyan, the Armenian opposition leader who helped force Armenia prime minister Serzh Sargsyan to resign on Monday, had called on his supporters to stage a rally on Wednesday.
Pashinyan has said he was ready to be the country's next premier and would keep up pressure on the ruling elite until it agreed to real change.
Pashinyan had been expected to sit down for talks with acting Prime Minister Karen Karapetyan to discuss political transition after Prime Minister Serzh Sargsyan abruptly stepped down on Monday amid massive anti-government protests.
Karapetyan said in a statement on Wednesday that the talks with Pashinyan were cancelled after the opposition came forward with unspecified "unilateral demands."
Karapetyan is an ally of Sargsyan, who ruled Armenia for 10 years, and the opposition insists he step down soon to make way for a new premier appointed by a new parliament. The talks on Wednesday were supposed to discuss that transition.
Pashinyan called on his supporters to take to the streets in protest.
About 5,000 people marched in the centre of the capital, Yerevan, blocking traffic and chanting "Join us!"
"We will not allow authorities to steal our victory," Pashinyan told supporters on Wednesday morning. "There will be more of us here with every day until we take power."