The Russian-brokered deal halted a six-week conflict between Azeri and ethnic Armenian forces over the region and its surrounding areas, locking in territorial gains for Azerbaijan.
Moscow has deployed peacekeepers to police the ceasefire, but skirmishes broke out on Sunday that Azerbaijan and Armenia each blamed on the other side. Four Azeri troops were reported killed in the fighting and six ethnic Armenians wounded.
In a new setback on Wednesday, Nagorno-Karabakh's defence ministry said it had lost contact with several military positions late on Tuesday in areas that were supposed to remain under its control according to the Nov. 10 ceasefire deal.
Azerbaijan's defence ministry could not immediately be reached for comment.Nagorno-Karabakh's ministry said it had failed to locate the troops despite carrying out search operations through the night.Hours later, regional head Arayik Harutyunyan said the troops had been captured and accused Azerbaijan of a "provocation".
"Several dozen servicemen were taken hostage by Azeri forces in the direction of Ktsaberd village, and the defence ministry is currently trying to figure out all the circumstances," Harutyunyan said in a pre-written speech posted on his Facebook page.The comments came shortly after Armenia and Azerbaijan confirmed they had begun exchanging groups of prisoners of war, part of an "all for all" swap mediated by Russia.