The five-day death toll in Azerbaijan rose to 16 on Thursday amid continued Armenian attacks on civilian settlements, said officials.

Azerbaijani prosecutors said in a statement that another civilian had succumbed to their wounds, adding that the number of those injured by Armenian forces in the city of Terter had risen to 55.

Border clashes broke out early Sunday when Armenian forces targeted Azerbaijani civilian settlements and military positions, leading to casualties.

Azerbaijan's parliament declared a state of war in some of its cities and regions following Armenia's border violations and attacks in the occupied Upper Karabakh, also known as Nagorno-Karabakh, region.

On Monday, Azerbaijan declared partial military mobilization amid the clashes.

Upper Karabakh conflict 

Relations between the two former Soviet nations have been tense since 1991, when the Armenian military occupied Upper Karabakh, an internationally recognized territory of Azerbaijan.

Four UN Security Council and two UN General Assembly resolutions, as well as many international organizations, demand the withdrawal of the occupying forces.

The OSCE Minsk Group -- co-chaired by France, Russia and the US -- was formed in 1992 to find a peaceful solution to the conflict, but to no avail. A cease-fire, however, was agreed upon in 1994.

France, Russia and NATO, among others, have urged an immediate halt to clashes in the occupied region.