BRUSSELS, September 27. /TASS/. High Representative of the EU for Foreign Affairs and Security Policy Josep Borrell on Sunday spoke over the phone with the Armenian and Azerbaijani top diplomats and called for immediate ceasefire.

"I spoke to ministers of Armenia and Azerbaijan and stressed the importance of an immediate ceasefire," he wrote on his Twitter account.

"There is no military solution to the conflict. The only way forward is the return to negotiating table without preconditions under OSCE Minsk Group co-chairs," he underscored.

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 ab 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. Armenia’s authorities have imposed martial law and announced mobilization of reservists.

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.