(Bloomberg) -- A cease-fire between Azerbaijan and Armenia was broken hours after coming into effect, with both sides trading accusations of violations early Sunday.

It’s the second truce brokered by Russia this month that has failed to stop fighting. Hundreds of people have been killed since the worst fighting in decades erupted between the countries over the breakaway region of Nagorno-Karabakh three weeks ago.

Armenian forces said 673 soldiers and 36 civilians have died since the fighting erupted Sept. 27. Azerbaijan hasn’t disclosed figures on military deaths and says 47 civilians have been killed.

Azerbaijan’s Defense Ministry said Armenia “grossly” violated the cease-fire that came into force at midnight, shelling Azeri positions in the Cabrayil district south of Nagorno-Karabakh. Armenia’s Defense Ministry Spokeswoman Shushan Stepanyan said Azerbaijani armed forces violated the agreement with an artillery barrage south of the enclave.

Armenians took control of Nagorno-Karabakh and seven surrounding districts of Azerbaijan during a war amid the collapse of the Soviet Union. That initial conflict was halted by a Russia-brokered truce in 1994. Mediation efforts since then by Russia, France and the U.S. have failed to resolve the dispute.

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