The foreign ministers of Russia and Iran have joined efforts to prevent a new war between Azerbaijani and Armenian forces over Nagorno-Karabakh, where both sides have accused the other of violating a two-day-old cease-fire.

The Russian and Iranian foreign ministers were meeting with their Azerbaijani counterpart in Baku on Thursday, and the Russian prime minister was due in the Armenian capital later in the day.

Fighting that erupted over the weekend has killed at least 64 people and is the worst outbreak of violence since a separatist war ended in 1994 and left Nagorno-Karabakh, officially part of Azerbaijan, under the control of local Armenian forces and the Armenian military.

Both sides on Thursday accused the other of violating the cease-fire, with Nagorno-Karabakh's military saying one of its soldiers was killed.