Azerbaijan said on Sunday that Armenian armed forces have shelled its second largest city Ganja, escalating the conflict which flared up last week.
In a statement, Azerbaijan's Defense Ministry said Armenian armed forces are firing rockets in Fizuli region from Armenia, and heavy artillery in Aghdam and Terter regions from "occupied territories."
The enemy shelled Ganja city from Armenia, it said.
Defense Minister Zakir Hasanov said shelling Azerbaijan's territories from Armenia is "provocative and expands the zone of hostilities."
Separately, Hikmet Hajiyev, an assistant to Azerbaijan's president, on Twitter said "indiscriminate missile attacks are launched against Ganja, Füzuli, Tartar and Jabrayil cities of Azerbaijan from territory of Armenia."
He added: "Ganja is the second biggest city of Azerbaijan. 500.000+ population."
Border clashes broke out last Sunday when Armenian forces targeted Azerbaijani civilian settlements and military positions, leading to casualties.
Upper Karabakh conflict
Relations between the two former Soviet republic have been tense since 1991, when the Armenian military occupied Upper Karabakh, an internationally recognized territory of Azerbaijan.
Multiple UN 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.
Many world powers including Russia, France, and the US have urged an immediate cease-fire.