Armenia accused Azerbaijani forces of striking the main city in the disputed Nagorno-Karabakh region on Friday as fighting raged for a sixth day.
Yerevan said it was ready to work with mediators for a ceasefire but Azerbaijan fired back and said that Armenia must first withdraw its troops.
Baku and Yerevan have for decades been locked in a seething conflict over the Armenian province that broke away from Azerbaijan in a fought war in the 1990s.
New fighting that started on Sunday has been the heaviest in decades and has claimed nearly 200 lives, including more than 30 civilians.
Intermittent shelling and ambulance sirens were heard in Stepanakert, the main city in Karabakh, throughout Friday, an AFP team reported.
Armenia said Azerbaijani forces attack Stepanakert wounding many people.
When Azerbaijan struck, ten emergency response workers had been injured. separatist authorities said.
International calls for the neighbours to halt clashes and begin talks have reinforce as fears grow that the fighting could expand into a multi-front war sucking in regional powers Turkey and Russia.
Azerbaijani forces had destroyed a bridge linking Armenia to Karabakh and vowed a counterstrike, the separatist government said.
There will be a proportionate response, a spokesman for the separatist leader said.
Azerbaijan said, Armenian forces were shelling a number of its settlements including the town of Terter.
The Foreign Office (FO) in Islamabad, meanwhile, rejected media reports that claimed Pakistan Army personnel were fighting alongside Azerbaijani forces against Armenian troops, terming the reports “speculative, baseless and irresponsible”.
FO spokesperson Zahid Hafeez Chaudhri said Pakistan was deeply concerned over the deteriorating security situation in the Nagorno-Karabakh region.
The intensive shelling by Armenian forces on civilian populations of Azerbaijan is reprehensible and most unfortunate,” he said, adding that the situation could “compromise peace and security of the entire region.
Armenia should stop its military action to avoid escalation in the crisis. He said Pakistan supported Azerbaijan’s position on Nagorno-Karabakh, in line with several unanimously adopted United Nations Security Council resolutions.