Azerbaijan’s President Ilham Aliyev has vowed to fight on until Armenian forces leave disputed territory, on the fourth day of fierce fighting in the region.
More than 100 deaths have been reported in the heaviest fighting in years over the Nagorno-Karabakh region.
Officially part of Azerbaijan, it is governed by ethnic Armenians.
The two former Soviet republics fought a war in 1988-1994 over the territory.
Although Armenia backs the self-declared republic it has never officially recognised it. It is unclear what caused the renewed fighting, which is the heaviest since the 1994 ceasefire, and there are growing fears international powers could be dragged into the conflict.