Azerbaijan's second-largest city, Ganja, has been shelled by Armenian forces, as heavy clashes continue over the disputed Nagorno-Karabakh region.

The enclave is officially part of Azerbaijan but run by ethnic Armenians.

The self-proclaimed authorities there say they hit Ganja's military airport after Azerbaijani forces shelled the region's capital, Stepanakert.

More than 100 people are now known to have been killed, including civilians, since the fighting began a week ago.

There are fears that the actual death toll could be much higher, as casualty claims from both sides have not been independently verified.

Armenia and Azerbaijan are blaming each other for the heaviest clashes since 2016.

Azerbaijan's military says its forces have retaken control over seven villages since Sunday, while Nagorno-Karabakh says its troops have "improved" their frontline positions.

Earlier this week, Armenia said it stood "ready to engage" with mediators from France, Russia and the US to try to agree a ceasefire.

Azerbaijan, which is openly backed by Turkey, has demanded the withdrawal of Armenian troops from Nagorno-Karabakh and adjacent areas seized by ethnic Armenian troops.

The two former Soviet republics went to war over the territory in 1988-94, eventually declaring a ceasefire. However, they have never reached a settlement over the dispute.

In a brief statement on Sunday, Azerbaijan's defence ministry said Armenian forces were shelling Ganja, the western Azerbaijani city lying to the north of Nagorno-Karabakh.

Defence Minister Minister Zakary Hasanov later said this was a "clearly provocative" move which was expanding the conflict.

Azerbaijan provided no official casualty or damage details in Ganja, although footage has emerged showing several destroyed buildings.

Meanwhile, Nagorno-Karabakh's authorities said on Sunday that Ganja's military airport used by Azerbaijani forces to attack Armenian civilians had been destroyed.

They said they had acted after Stepanakert was hit by missiles. Heavy casualties were reported in the city, which was left without electricity, according to Armenpress news agency.

It quoted the region's leader, Arayik Harutyunyan, as warning that "from now on the military facilities permanently deployed in Azerbaijan's major cities are legitimate targets of the defence army".