MOSCOW, July 18 (RIA Novosti) - Discussions on Saturday between the presidents of Russia, Armenia and Azerbaijan on a settlement to the Nagorny Karabakh dispute were held in a constructive atmosphere, a Russian presidential aide said.

"In the course of today's meeting, already the fourth, between the presidents of Russia, Azerbaijan and Armenia, Dmitry Medvedev confirmed Russia's readiness as a co-chair of the Minsk Group to make efforts going forward to find a mutually acceptable conclusion for a settlement in Nagorny Karabakh," Medvedev's aide Sergei Prikhodko said.

Azerbaijani President Ilham Aliyev and his Armenian counterpart, Serzh Sargsyan, held bilateral talks in Moscow on Friday before Saturday's discussions with Medvedev.

"There was a long and, according to our side, very constructive meeting during which some of the remaining open questions were discussed," Prikhodko said.

"Presidents Aliyev and Sargsyan expressed their gratitude to Dmitry Medvedev for his efforts to bring together the positions of Armenia and Azerbaijan," he added.

The latest talks focused on the principles for resolving the dispute agreed at an internationally mediated conference in Madrid in 2007.

Nagorny Karabakh, a region in Azerbaijan with a largely Armenian population, has been a source of conflict between the former Soviet republics since the late 1980s. The province has its own government and is de facto independent.

The co-chairs of the Minsk Group - the United States, Russia and France - said during the G8 summit in Italy earlier this month that they would submit a revised set of proposals on the disputed region, and that any agreement must be based on the Madrid accord.

The war between Azerbaijan and Armenia over the mountainous enclave in 1988-1994 left an estimated 35,000 people dead. Sporadic violence on the border has continued ever since.