An overnight fire that broke out in the barracks of an Armenian military unit left 15 servicemen dead and three others in serious condition, the country's defence ministry said Thursday.

"According to preliminary information, 15 servicemen were killed as a result of a fire that broke out in the barracks of an engineer and sniper company of a military unit... and the condition of three servicemen is assessed as serious," the ministry said in a statement.

According to the ministry, the fire broke out at around 01:30 am on Thursday (2130 GMT Wednesday) in the village of Azat in Armenia's eastern Gegharkunik region.

It said the cause of the fire was not yet established.

Last August, more than a dozen people were killed in an explosion and subsequent fire at a busy market in Armenia's capital Yerevan.

The Caucasus nation of around three million people is still recovering from a 2020 war with Azerbaijan, which ended in a heavy defeat and sparked a political crisis.

Despite the end of the large-scale fighting, tensions persist between the ex-Soviet rivals over their borders.