Azerbaijan said Sunday that its second-largest city, Ganja, was under attack from Armenian forces, marking a new escalation in the conflict over the disputed Nagorno-Karabakh region.

Fighting over the ethnic Armenian enclave inside Azerbaijan erupted a week ago and has intensified in recent days despite international calls for a halt to hostilities. More than 240 people have died, with both sides accusing each other of targeting civilians.

Azerbaijan's Defense Ministry said in a statement that one civilian was killed and four were wounded in the attack on Ganja, a city of some 330,000 inhabitants in the country's west. It added that several other civilian areas, including the cities of Terter and Horadiz, had also come under fire from rockets and shelling.

Read more: Nagorno-Karabakh: Armenia 'stands ready' for peace talks

Cities under fire

Armenia denied that it had fired on Azerbaijani cities. However, the Armenian leader of Nagorno-Karabakh said that his forces had destroyed an airbase in Ganja.

"Permanent military units located in the large cities of Azerbaijan from now on become the targets of the defense army," Arayik Harutyunyan said in a post on Facebook. "I call on the residents of these cities to immediately leave."

Meanwhile, Armenia said the Karabakh capital, Stepanakert, and the city of Martakert were under attack by Azerbaijan's air force and from long-range missiles.

The International Committee of the Red Cross (ICRC) on Sunday condemned the indiscriminate shelling, saying it violated international law. 

"The ICRC strongly condemns ... the alleged unlawful attacks using explosive weaponry in cities, towns and other populated areas," said Martin Schuepp, ICRC's Eurasia regional director in Geneva.

Bluster from Baku

On Sunday, Azerbaijani President Ilham Aliyev delivered a fiery address demanding that Armenia admit that Nagorno-Karabakh belongs to Azerbaijan.

"Nagorno-Karabakh is our land. We have to go back there, and we are doing it now," Aliyev said, adding that Armenian forces "must leave our territories, not in words but in deeds." 

Nagorno-Karabakh is an Armenian enclave region officially part of Azerbaijan but currently controlled by Armenian forces. Azerbaijan has repeatedly threatened to take back the territory by force. 

"The leadership of Armenia should think carefully before it is too late," Aliyev said.

Read more: Armenia shoots down drones near capital

Simmering conflict

Azerbaijan and Armenia have for decades been locked in a simmering conflict over the Karabakh region, which broke away from Baku in a 1990s war that claimed 30,000 lives. The latest fighting is the worst since a 1994 truce between the two former Soviet republics.

There are fears the ongoing clashes could escalate into a full-scale war drawing in other powers such as Turkey and Russia.

Russia, the United States and France, whose leaders are part of a mediation group seeking a resolution to the conflict, this week called for an immediate cease-fire.

wmr,nm/sms (Reuters, AFP, dpa)