Azerbaijan said on Sunday that Armenian forces had fired rockets at its second-largest city of Ganja, killing one civilian and wounding four, and threatened to retaliate by destroying military targets inside Armenia.

The developments marked a sharp escalation of the war in the South Caucasus that broke out a week ago.

The main fighting so far has been between Azerbaijan and Nagorno-Karabakh, an ethnic Armenian enclave inside Azerbaijan, but it now threatens to spill over into a direct war with Armenia itself.

"Azerbaijan will destroy military targets directly inside Armenia from which shelling of its population centers is taking place," presidential aide Hikmet Hajiyev said.

He said there were also civilian casualties in another Azeri region, Beylagan, which borders Nagorno-Karabakh.

Escalating conflict: Competing claims as Azerbaijan-Armenia fighting continues

Armenia says it is ready to work for Nagorno-Karabakh ceasefire

Armenia denied it had directed fire "of any kind" towards Azerbaijan. The leader of Nagorno-Karabakh said his forces had targeted a military airbase in Ganja but later stopped firing in order to avoid civilian casualties.

The conflict threatens to drag in other regional powers as Azerbaijan is supported by Turkey, while Armenia has a defense pact with Russia.

Turkey's Foreign Ministry said, "The attacks of Armenia targeting the civilians in Ganja ... are a new manifestation of Armenia's unlawful attitude. We condemn these attacks."

Turkey accused Armenian forces of "violating all principles of humanitarian law and attacking civilian settlement areas besides the occupied regions, the scene of clashes."

"Those attacks show ... Armenia will not hesitate to commit a crime of humanity in order to continue its illegal occupation," the ministry said, branding the country as "the biggest obstacle to peace and stability in the region."

(With input from Reuters and AFP)

(Cover: Emergency personnel work at a damaged area of the city of Ganja following a reportedly Armenian rocket strike during the ongoing fighting between Armenia and Azerbaijan over the breakaway Nagorno-Karabakh region, October 4, 2020. /AFP)