Russia hosted the foreign ministers of Armenia and Azerbaijan for separate talks this week as world powers seek to step up hitherto failed efforts to agree a lasting truce to halt fighting over Nagorno-Karabakh.
Russian Foreign Minister Sergei Lavrov met Azerbaijani Foreign Minister Jeyhun Bayramov and his Armenian counterpart Zohrab Mnatsakanyan for separate talks on Tuesday and Wednesday, Lavrov's ministry said in a statement.
But the two ministers from the Caucasus rivals had no face-to-face encounter in the Russian capital.
Russia, the United States and other world powers are seeking to step up efforts to persuade both sides to stop fighting that has left hundreds of people dead after two purported ceasefire accords never showed the slightest sign of holding.
The ministers visited Moscow ahead of meetings with U.S. Secretary of State Mike Pompeo on Friday. A trilateral meeting in Washington has also been ruled out and they will meet Pompeo separately.
In Russia, the chief diplomats discussed "urgent matters related to the implementation of agreements to halt fire and creating conditions for a lasting settlement" of the Karabakh conflict, the statement said.
Azerbaijan's foreign ministry said only that its top diplomat had travelled to Moscow "for consultations."
Armenian foreign ministry spokeswoman Anna Nagdalyan said Mnatsakanyan met Lavrov on Wednesday.
Two broken truces
A truce was agreed in Moscow earlier this month after 11 hours of talks, but the accord had next to no impact on the ground.
A second ceasefire agreed Saturday fell apart almost immediately.
Yerevan says 772 Armenian soldiers and 36 civilians have been killed in the flare-up of fighting.
Baku has reported 63 civilian casualties but has yet to disclose military losses.
Azerbaijan and the Armenian separatists who control its Karabakh region have been locked in a bitter impasse over the fate of the mountainous province since a war in the 1990s that left 30,000 people dead.
Their long-simmering conflict erupted again on September 27 in fierce clashes that raised the alarm over the failure of decades-long international mediation.
Along with France and Russia, the United States co-chairs the so-called Minsk Group of international mediators to the Karabakh peace talks since the 1994 ceasefire.
Baku says its forces have captured ground within Karabakh and that it also now controls other Azerbaijani territory that had been held by Armenian forces.
Azerbaijan's President Ilham Aliyev has said there can only be a ceasefire when Aremenia pulls out from Karabakh and all the surrounding regions of Azerbaijan held by Armenian forces.
However Armenian Prime Minister Nikol Pashinyan has urged international recognition of Karabakh, claiming its inhabitants would not be safe under Azerbaijani rule.