YEREVAN, September 28. /TASS/. Azerbaijani troops have launched a large-scale offensive in the north and south on Nagorno-Karabakh, with fierce fighting being reported from the area, Armenian defense ministry spokesman, Artsrun Ovannisyan, said on Monday.

"The Azerbaijani army has staged a large-scale offensive in the Araksa Valley (south) and at the Matagis-Talish section (south). The Artsakh (non-recognized Nagorno-Karabakh republic) defense army is repelling the attacks," he wrote on Facebook.

The situation in Nagorno-Karabakh escalated on September 27, when Azerbaijan said its positions had come under extensive fire from Armenia. Armenia, in turn, said the Azerbaijani army had staged an offensive in the direction of Nagorno-Karabakh. It said a number of settlements in Nagorno-Karabakh, including its administrative center Stepanakert, had come under shelling by Azerbaijan. Both sides report casualties, including among civilians. Both Armenia and Azerbaijan have imposed martial law. Mobilization of reservists has been announced in Armenia. Azerbaijan has announced partial mobilization.

The conflict between Armenia and Azerbaijan over the highland region of Nagorno-Karabakh, a disputed territory that had been part of Azerbaijan before the Soviet Union break-up, but primarily populated by ethnic Armenians, broke out in February 1988 after the Nagorno-Karabakh Autonomous Region announced its withdrawal from the Azerbaijan Soviet Socialist Republic. In 1992-1994, tensions boiled over and exploded into large-scale military action for control over the enclave and seven adjacent territories after Azerbaijan lost control of them. Talks on the Nagorno-Karabakh settlement have been ongoing since 1992 under the OSCE Minsk Group, led by its three co-chairs - Russia, France and the United States.