Six Armenian soldiers were captured by Azerbaijan Thursday, the latest in a series of escalating border incidents after last year’s war over the disputed Nagorno-Karabakh region.

The capture of Armenia’s soldiers comes at a delicate time for Prime Minister Nikol Pashinyan ahead of snap elections next month.

The Armenian defence ministry said in a statement that its forces were carrying out engineering work in a border region when Azerbaijan’s army “surrounded and captured six servicemen”.

Also Read: Joe Biden condemns Tigray violence, calls for end of human rights abuses

Azerbaijan’s military however described the Armenian soldiers as a “reconnaissance and sabotage group” in a statement announcing the detention.

It said the Armenian soldiers had “tried to mine supply routes leading to Azerbaijan army positions” and “were surrounded, neutralised and taken prisoner”.

The incident, which Azerbaijan said took place in the Kelbajar region on the border between the historic rivals, is just the latest in several months and puts additional pressure on a ceasefire brokered by Russia last year.

Last year the two ex-Soviet countries in the Caucasus region fought for six weeks for control of Nagorno-Karabakh, an ethnic Armenian region in Azerbaijan that had been controlled by separatists for decades.

Some 6,000 people were killed in the conflict which ended after Moscow brokered an agreement between Yerevan and Baku that saw Armenia hand to Azerbaijan large sections of territory it had controlled for decades, including Kelbajar.

Also Read | It’s a wrap: Antony Blinken’s finishing touch to Israel-Gaza conflict

The ceasefire, monitored by some 2,000 Russian peacekeepers, has largely held but tensions have persisted and there have been several border incidents.

Armenia said one of its soldiers was killed earlier this week after shooting broke out with Azerbaijan’s forces, an incident Baku denied it was responsible for.

Armenia had earlier in the month accused Azerbaijan’s military of crossing its southern border to “lay siege” to a lake that is shared by the two countries.

The latest escalation comes ahead of key parliamentary polls in Armenia on June 20.

Pashinyan announced the polls under pressure from opposition groups and street demonstrators, who for months after the war staged rallies demanding the prime minister’s resignation.

They hold him accountable for what many in Armenia believe was a humiliating defeat at the hands of Azerbaijan’s technologically superior army, and for agreeing to hand over swathes of territory to Azerbaijan.

Also Read: Top China, US trade officials hold candid first talks

Pashinyan has insisted he handled the war correctly, saying he had no choice but to concede or see his country’s forces suffer even bigger losses.

He maintains that fresh elections are the best way to end the post-war political stalemate.

Analysts say Pashinyan, 45, will likely retain his grip on power after the election.

Earlier this month, Pashinyan said Armenia and Azerbaijan were in talks mediated by Russia on the delimitation and demarcation of their shared borders.

He also said the two governments could discuss possible territorial swaps between the two countries.

Russia’s role as a broker between Armenia and Azerbaijan has largely come at the expense of Western powers including France and the United States.

All three are part of a mediating group that had tried but failed for decades to find a lasting solution to the conflict.

Ethnic Armenian separatists in Nagorno-Karabakh broke away from Azerbaijan around the collapse of the Soviet Union in a conflict that claimed the lives of some 30,000 people and displaced many more.