An opposition leader and several dozen other protesters were injured on Monday in Armenia as thousands of people rallied against a move by the ex-president to maintain a chokehold on power.
Police used stun grenades against protesters who sought to break through a barbed wire cordon in the centre of the capital Yerevan in an effort to get to the parliament building during rallies against former president Serzh Sarkisian.
The pro-Moscow politician ended his second and final presidential term last week but has been nominated by the ruling party for the post of prime minister.
The opposition says a new parliamentary system of government will allow Sarkisian, 63, to maintain huge influence under a new parliamentary system of government.
During the rallies, dozens were injured, including opposition leader Nikol Pashinian -- who called the protests -- and a number of police officers.
Authorities said 46 people - including six police -- sought medical help.
Pashinian, who received injuries to his arms and face, was briefly taken to hospital.
Authorities called on him to end the protests and threatened to break up the rallies with force. But Pashinian later returned -- sporting a bandaged arm -- and vowed to continue the demonstrations.
Extra police and a water cannon have been deployed in the city centre, while prosecutors opened a criminal probe over mass riots in the capital.
The ruling Republican Party and the government-friendly Dashnaktsutyun Party formally nominated Sarkisian as candidate for the post of prime minister on Monday despite the protests.
He is expected to be elected by parliament on Tuesday.
Earlier on Monday, demonstrators marched through the centre of Yerevan and blocked streets after Pashinian called on Armenians to prevent Sarkisian's political transition.
Some chanted "Armenia without Serzh" and "Serzh is a liar."
"Our goal right now is to prevent Serzh Sarkisian from becoming the country's leader for a third time without violence and the use of force," said Pashinian.
Several hundred people sat or laid down on pavements, blocking roads leading to the parliament building and universities.
Some built barricades using cast-iron benches and metal trash cans.
Parliamentary vice-speaker Eduard Sharmazanov, who is the ruling party's spokesman, dismissed the protests as "the opposition's artificial and fake agenda".
"No one will prevent us from voting tomorrow for our candidate Serzh Sarkisian," he told AFP.
The rallies began on Friday when more than 4,000 people took part.
A shrewd former military officer, Sarkisian has been in charge of the landlocked South Caucasus nation of 2.9 million since winning a presidential vote in 2008.
The country's new figurehead president, Armen Sarkisian, was sworn in last week but his powers will be weaker under a new parliamentary system of government.
The two men are not related.
Opposition politicians say the shift to a parliamentary republic with a powerful prime minister has been designed to increase Serzh Sarkisian's grip on power in the impoverished Moscow-allied country.
Tensions in Armenia often flare up during presidential and parliamentary elections.
After Sarkisian was first elected president in February 2008, 10 people died in bloody clashes between police and supporters of the defeated opposition candidate.