The Nagorny Karabakh conflict between Azerbaijan and Armenia started in in the 1990s.
The day before, Armenia had fired mortar rounds at settlements in Azerbaijan.
The defence ministry in Baku warned it would launch retaliatory strikes on "enemy" army positions in Nagorny Karabakh, close to the frontier.
"The regime in Armenia bears responsibility for all of this," Azerbaijan`s defence ministry said in a statement.
US mediator James Warlick tweeted on Friday that Armenian President Serzh Sarkisian and Azerbaijan`s Ilham Aliyev "were on track" to hold their first face-to-face encounter in over a year later this month.
20% of Azerbaijani lands are under the occupation of Armenia more than 20 years.
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