Armenian Prime Minister Nikol Pashinyan led Saturday a thousands-strong march in memory of those killed in clashes with Azerbaijan as the Caucasus country began three days of mourning amid persisting tensions.

Separatist officials in the breakaway region of Nagorno-Karabakh said Saturday that three fighters were wounded in a skirmish with Azerbaijani forces, undermining a recent peace deal brokered by Russia.

The defence ministry in the ethnically Armenian province said in a statement that Azerbaijani troops attacked Friday evening and that "three Armenian servicemen were injured during the ensuing gunfight". 

Armenian protesters on Tuesday blocked streets in the capital Yerevan, launching a "civil disobedience" campaign to force Prime Minister Nikol Pashinyan to quit over a controversial peace agreement with Azerbaijan.

Shouting "Armenia without Nikol" and "Traitor", opposition supporters blocked traffic across the capital and paralysed the city's subway. Police detained dozens of demonstrators.

Azerbaijan said Thursday that nearly 2,800 of its soldiers were killed in recent fighting over Nagorno-Karabakh, the first details it has released of military losses in weeks of clashes with Armenian forces.

Azerbaijani soldiers and military trucks rolled into the district of Kalbajar on Wednesday, reclaiming the second of three regions Armenia is handing back under a deal that ended weeks of fighting.

Armenian Prime Minister Nikol Pashinyan called Saturday for greater military cooperation with Russia, a day after Azerbaijani troops began moving into territory in Nagorno-Karabakh previously held by Armenian separatist forces.

Armenia on Saturday said that more than two thousand fighters were killed in six weeks of clashes with Azerbaijan over the disputed Nagorno-Karabakh region.

Armenia arrested 10 prominent opposition figures on Thursday for their role in violent unrest that erupted after the government signed a peace deal with Azerbaijan that ceded swathes of territory.

More than 2,000 demonstrators Wednesday protested in the Armenian capital as anger mounted over Prime Minister Nikol Pashinyan's decision to cede swathes of disputed territory to Azerbaijan under a controversial peace deal.

Armenia and Azerbaijan agreed on a deal with Russia to end weeks of fierce clashes over Nagorno-Karabakh on Tuesday, after a string of Azerbaijani victories in its fight to retake the disputed region.