Memorials marking the anniversary of the massacre of 1.5 million Armenians by Ottoman forces in 1915 took place a day after Prime Minister Serzh Sarkisian resigned (Photo: AFP)

Tens of thousands of Armenians led by opposition leader Nikol Pashinyan marched on Tuesday to honour 1.5 million of their kin killed by Ottoman forces in 1915, a day after the country's prime minister resigned following more than a week of opposition rallies.

The commemorations, which are a hugely emotional event for the South Caucasus country, came after Serzh Sarkisian on Monday stunned the country by standing down from his new post as prime minister.

Sarkisian, who had previously spent a decade in power as president, was accused of a blatant power grab by the opposition, who staged days of rallies in protest.

Clutching a purple rose, the bearded Pashinyan, 42, led a huge crowd of his supporters on a commemorative march to a hilltop memorial in the capital Yerevan to honour the victims of the World War I-era killings.

Sporting his trademark khaki-coloured T-shirt and a bandaged hand, Pashinyan -- who on Wednesday is expected to hold talks on the transfer of power -- called on the marchers to avoid shouting political slogans.

The acting head of government, Karen Karapetyan, appealed for unity after the wrenching political turmoil in a country locked in a simmering territorial conflict with Azerbaijan.

Russia -- which has a military base in Armenia -- appealed for stability but said it would not interfere.

Many Armenians said it was important the country managed to avoid bloodletting ahead of the highly symbolic commemorations.

"Thank God Armenian blood was not shed on the eve of the Genocide Remembrance Day," Seyran Halachyan, 58, told AFP at the foot of the hilltop memorial, the country's most visited landmark.

Ashot Minasyan, 72, said he was grateful to Sarkisian for not crushing peaceful protests and "leaving without bloodshed".

Acting government head Karapetyan thanked all political forces for heeding his call for unity.

"We are going through a difficult new phase in our history," he said in a statement.

"Today we show the world that despite difficulties and unresolved domestic issues we are together and united. This is our duty to the genocide's innocent victims."

Earlier in the day he also held official commemorations at the hilltop Tsitsernakaberd memorial, with thousands laying flowers at the monument.

Protest leader Pashinyan said that on Tuesday he would conduct "political consultations" to discuss a number of concrete steps so that a people's victory "could be legally guaranteed".

He has said that parliament would have to elect a new prime minister within a week and that snap parliamentary elections were also on the cards.

Many said they felt mixed emotions because the impoverished country's future was uncertain.

"I've been thinking from the start of the day that everything is just beginning," said Asya Bagdasaryan, 43.

"What awaits us in the future? Will there be new shocks?"

Armenia -- which depends on investment and aid from Russia -- over the past few years has been hit hard by economic troubles in the former Soviet master.

Unemployment in Armenia stood at 18 percent last year. The opposition says some 290,000 people have left the country since Sarkisian came to power in 2008.

Political turmoil enveloped the impoverished country of 2.9 million people after Sarkisian was last week elected prime minister by lawmakers after serving two successive presidential terms.

The opposition charged that the 63-year-old wanted to extend his grip on power under a new parliamentary system of government, saying he failed to tackle poverty and corruption.

Protests broke out several days before his expected election, with tens of thousands of people eventually taking to the streets of Yerevan and other cities in largely peaceful protests.

Sarkisian initially refused to resign but quit on the 11th day of demonstrations after a number of serving servicemen joined the marches.

His resignation came as a shock, with analysts saying just last week that the opposition did not have enough resources to force the veteran leader to quit.

Kremlin spokesman Dmitry Peskov expressed hope that the country's new leader would suit "all forces representing the Armenian people".

A spokesman for Azerbajan's foreign ministry expressed the hope that new Armenian authorities would adopt a "constructive" approach over the breakaway region of Nagorny Karabakh.