Armenia and Azerbaijan on Saturday blamed each other for failing to resolve their long and often violent dispute over the territory of Nagorno-Karabakh.

In a meeting Friday in the Russian city of Kazan, Armenian President Serzh Sarkisyan and his Azeri counterpart, Ilham Aliyev, were unable to agree on a basic principles agreement that would have set the stage for a settlement over the disputed ethnic Armenian enclave in Azerbaijan.

Armenian Foreign Minister Edward Nalbandian said the summit failed because Azerbaijan demanded too many changes to the latest version of the document.

Azerbaijan was quick to respond. A government official, Novruz Mamedov, said the Armenian leadership was misleading the international community to achieve its objectives.

But the two sides pledged to continue talks.

The two sides have been under increasing international pressure to sign the principles. U.S. President Barack Obama telephoned the two leaders Thursday to strongly encourage signing.

Twenty years ago, Armenia and Azerbaijan fought a war over Nagorno-Karabakh that ended in a 1994 cease-fire. Since then, talks have dragged on without resolution and the enclave has been under the control of Armenian forces. But despite the suspension of hostilities, exchanges of gunfire continue along the borders of the disputed region.

The conflict left 35,000 dead and forced as many as 1 million people from their homes.

Repeated international efforts to broker a peace deal have failed.