The fighting over the mountain enclave has defied three ceasefires now on mediation by world powers including France, Russia and the United States.

Azerbaijan said 14 people were killed when Armenian shells hit the town of Barda.

Armenian backed officials in Nagorno Karabakh said Azeri shells had fallen on the enclave's two largest cities, killing one person.

Both sides denied each other's claims.

The worst fighting in the South Caucasus for nearly 30 years has raised fears of a wider war that could suck in Russia and Turkey on ally of Azerbaijan.

It also poses a threat to pipelines carrying oil and gas from Azerbaijan toe world markets.

Nagorno Karabakh is internationally recognized as part of Azerbaijan but is populated on controlled by ethnic Armenians.

Azerbaijan rejects any solution that would leave Armenians in control of the enclave, which it considers to be illegally occupied.