The International Crisis Group has said tension between Armenia and Azerbaijan saw an “unprecedented” escalation last month when at least four people were killed in armed clashes near the rebel region of Nagorno-Karabakh.

“The nature of the reported clashes and ominous statements by some government officials mark an escalation unprecedented in recent years,” the group said in a statement on its website. “Both sides blamed each other for the uptick in violence.”

Armenians captured nearly 20 percent of Azerbaijan’s internationally-recognized territory, including Nagorno-Karabakh and seven surrounding districts, in a war after the Soviet Union’s breakup in 1991.

About 12,000 Azerbaijani nationals were killed and 1 million displaced before Russia brokered a ceasefire in 1994.

The sides have yet to sign a peace agreement despite more than 20 years of talks mediated by the US, Russia and France.

ANN.Az