Armenia's Defence Ministry said on Thursday that Azerbaijan had begun intensively shelling its military positions in Armenia's Gegharkunik province, the TASS news agency reported.
Azerbaijan said earlier on Thursday that one of its soldiers had been killed on the border with Armenia in what it described as an Armenian "provocation."
Armenia and Azerbaijan agreed to a ceasefire at their border on November 16 after Russia urged them to step back from confrontation following the deadliest clash since a war last year.