Police in Armenia have detained an opposition MP who has been leading anti-government protests, BBC News reported.
Nikol Pashinyan was picked up after Prime Minister Serzh Sargsyan cut short a televised meeting between the two. During their three-minute confrontation Mr Pashinyan insisted that the PM should resign. Mr Sargsyan said it was "blackmail" and walked out.
The opposition argues that a recent constitutional change is an effort by Mr Sargsyan to retain power. The move - approved by parliament on Tuesday - strengthens the role of prime minister, which Mr Sargsyan only took on last week. He stepped down as president after reaching his two-term limit.
Sunday's events began with a meeting - attended by dozens of journalists - between Mr Sargsyan and Mr Pashinyan at a hotel in the capital Yerevan.
The exchange was brief. After the prime minister said he was glad his rival had "responded to my numerous appeals to negotiate", Mr Pashinyan struck an uncompromising note.
"I think there is a misunderstanding," he said. "I have come here to discuss the terms of your resignation and the terms of a peaceful and smooth transition of power."
Mr Sargsyan said that "this is not a dialogue, this is blackmail", and left.
Addressing the assembled reporters afterwards, Mr Pashinyan called on his supporters to continue their protests, which have continued for more than a week.
He was detained shortly afterwards, as riot police were dispersing thousands of protesters in Yerevan. His whereabouts are unclear.
