Armenia and Azerbaijan negotiated a ceasefire to end a flare-up of fighting that has killed 155 soldiers from both sides, a senior Armenian official said early on Thursday.

Armen Grigoryan, the secretary of Armenia’s Security Council, announced the truce in televised remarks, saying it took effect five hours earlier, at 8pm local time on Wednesday.

A previous ceasefire that Russia brokered on Tuesday quickly failed.

The truce announcement followed two days of heavy fighting that marked the largest outbreak of hostilities between the two longtime adversaries in nearly two years.

Shortly before Mr Grigoryan’s declaration, thousands of protesters took to the streets of Armenia’s capital accusing Prime Minister Nikol Pashinyan of betraying his country by trying to appease Azerbaijan and demanding his resignation.

Armenia and Azerbaijan traded blame for the hostilities, with Armenian authorities accusing Baku of unprovoked aggression and Azerbaijani officials saying their country was responding to Armenian shelling.

Mr Pashinyan said 105 of his country’s soldiers had been killed since fighting erupted early on Tuesday, while Azerbaijan said it lost 50.

Azerbaijani authorities said they were ready to unilaterally hand over the bodies of up to 100 Armenian soldiers.

The ex-Soviet countries have been locked in a decades-old conflict over Nagorno-Karabakh, which is part of Azerbaijan but has been under the control of ethnic Armenian forces backed by Armenia since a separatist war there ended in 1994.

During a six-week war in 2020, Azerbaijan reclaimed broad swaths of Nagorno-Karabakh and adjacent territories held by Armenian forces.

More than 6,700 people died in the fighting, which ended with a Russia-brokered peace deal. Moscow deployed about 2,000 troops to the region to serve as peacekeepers under the deal.

Mr Pashinyan said on Wednesday that Azerbaijani forces have occupied 10 square kilometres (nearly 4sq m) of Armenia’s territory since the fighting began.

He told legislators that his government has asked Russia for military support under a friendship treaty between the countries, and also requested assistance from the Collective Security Treaty Organisation (CSTO).

“Our allies are Russia and the CSTO,” Mr Pashinyan said, adding that the collective security pact states that an aggression against one member is an aggression against all.

“We don’t see military intervention as the only possibility, because there are also political and diplomatic options,” Mr Pashinyan said, speaking in his nation’s parliament.

He told legislators that Armenia is ready to recognise Azerbaijan’s territorial integrity in a future peace treaty, provided that it relinquishes control of areas in Armenia its forces have seized.

Some in the opposition saw the statement as a sign of Mr Pashinyan’s readiness to cave in to Azerbaijani demands and recognise Azerbaijan’s sovereignty over Nagorno-Karabakh.

Thousands of angry protesters quickly descended on the government’s headquarters, accusing Mr Pashinyan of treason and demanding he step down.

Mr Pashinyan angrily denied reports alleging that he had signed a deal accepting Azerbaijani demands as an “information attack”.

Arayik Harutyunyan, the leader of Nagorno-Karabakh, reacted to the uproar by saying that the region will not agree to come into the Azerbaijani fold and will continue pushing for its independence.