Armenia's governing party on Monday was set to win parliamentary elections that were the biggest test of the country's fragile democracy since 2008 polls ended in fatal clashes, partial results showed.

President Serzh Sarkisian's Republican party led with 44.41 percent of the vote after more than three-quarters of the 1,982 polling stations had counted ballots from Sunday's contest, the Central Election Commission said.

Its outgoing coalition partner turned poll rival, the Prosperous Armenia party, was running second on 30.52 per cent.

Trailing far behind, the opposition Armenian National Congress bloc was third on 6.85 percent, according to the commission results, posted on its website.

The bloc needs to pass a seven-percent threshold to enter parliament, higher than the five-percent threshold for individual parties.

The elections were monitored by 350 European observers led by the Organisation for Security and Cooperation in Europe, which is due to deliver its initial verdict on the conduct of the vote later on Monday.

The authorities had promised a clean contest for the 131-seat National Assembly in the hope of avoiding a repeat of the clashes between riot police and opposition supporters four years that left 10 people dead.

"I want everything to be calm, peaceful and in accordance with our laws today, tomorrow and the day afterwards," Sarkisian told journalists after casting his ballot in Yerevan on Sunday.

But a monitoring alliance including Prosperous Armenia and the Armenian National Congress opposition bloc led by former president Levon Ter-Petrosian expressed "doubts about the legitimacy of the electoral process".

Ter-Petrosian's bloc, which led the protests against the alleged 2008 vote-rigging that ended in violence, has threatened new protests if there is evidence of large-scale fraud.

The partial results showed the bloc running third on 6.38 percent -- just below the threshold required to enter parliament.

Local media reported allegations of polling-day violations including incidents of parties bribing voters -- a problem that has marred previous Armenian elections.

It was not immediately clear though how widespread such irregularities were.

Campaigning in the Caucasus state of 3.3 million people mainly focused on issues of unemployment, poverty and emigration rather than Armenia's long-running political disputes with neighbours Turkey and Azerbaijan.

Landlocked and impoverished Armenia has suffered economically because its borders with both countries are closed.

No final peace deal has been signed with Azerbaijan since the 1990s war over the region of Nagorny Karabakh, and gun battles often erupt along the front line.

Efforts to restore diplomatic relations with Turkey, which could have ended decades of enmity over the World War I genocide of Armenians under the Ottoman empire, have also been frozen.