Armenia's prosecutor general on Thursday opened a criminal case into "an infringement of territorial integrity" by Azerbaijan, Russia's news agency RIA said, after Armenia's defence ministry accused Azerbaijan of moving forces into its territory.
Armenia and Azerbaijan remain at loggerheads after the latest bloody conflict over the Nagorno-Karabakh enclave last year that locked in territorial gains for Azerbaijan and was eventually brought to a halt by a Russian-brokered ceasefire.
Armenia's defence ministry said Azeri armed forces on Thursday "carried out another provocation against the sovereign territory of the Republic of Armenia, trying to ensure positional advance in the border areas of Vardenis and Sisian."
The ministry said the Armenian side stopped the Azeri advance and forced its troops to return to their positions.
Azerbaijan dismissed the accusations, saying it was enforcing its own border and is committed to easing tensions in the region, its foreign ministry said late on Thursday.
The Azeri ministry called Armenia's reaction to the developments "inadequate" and "provocative", adding that Azeri officials were was in talks with Armenian border guards.
(Reporting by Andrey Ostroukh; additional reporting by Nailia Bagirova in Baku)
