Azerbaijani forces attacked the cities of Stepanakert and Shushi on Saturday morning, targeting them with missile and artillery strikes, according to the Artsakh Defence Army (military of the self-proclaimed Republic of Artsakh).
At the same time, Baku claimed that Armenian forces had shelled several settlements in Karabakh.
"The armed forces of Armenia, which grossly violated the humanitarian ceasefire, are shelling the territories of Terter, Aghdam, Barda and Agjabedi districts this morning", the Azerbaijani Defence Ministry said.
The Nagorno-Karabakh conflict began in 1991, when the predominantly Armenian-populated region proclaimed independence from Azerbaijan. After that, Baku and Yerevan waged a full-scale war for the region between 1992 and 1994, which resulted in the deaths of around 40,000 troops and civilians on both sides.
A ceasefire was mediated by the OSCE Minsk Group in 1994, but the conflict remained frozen, and the self-proclaimed Nagorno-Karabakh Republic continues be an unrecognised state.