"Based on the information about the recruitment and use of foreign mercenaries by Azerbaijan since the first days of the aggressive war, the Armenian central military prosecutor's office has launched a criminal case into international terrorism," the Prosecutor General's Office said in a press release.
Azerbaijan has "forced the mercenaries to continue the military action against the Republic of Artsakh [Nagorno-Karabakh] in the Horadiz area amid the declared ceasefire," the press release stated.
The Armenian prosecutor's office also said it has information the mercenaries partook in the attacks on the Hadrut city as a result of which "houses were burnt, civilian people were brutally killed and servicemen of the Artsakh Defence Army died."
"As defined by international legal acts, the entire toolkit of cooperation and mutual legal assistance with states concerned is currently being used to fully solve this crime and bring those responsible to justice," the press release read.
The fighting on the line of contact in Nagorno-Karabakh started on September 27. Azerbaijan and Armenia have been accusing each other of starting the firing, as civilian settlements in the self-proclaimed Nagorno-Karabakh republic came under heavy artillery fire.
Last week, as the fighting continued, Russian President Vladimir Putin invited the foreign ministers of Azerbaijan and Armenia to come to Moscow and meet with their Russian counterpart in a bid to negotiate a ceasefire.
The negotiation lasted for almost 11 hours and resulted in an agreement on a humanitarian ceasefire beginning at noon on October 10. The parties agreed on a pause in order to exchange prisoners and bodies of killed soldiers as well as negotiate additional details of the ceasefire.
The international community strongly condemned the escalation in Nagorno-Karabakh. The co-chairs of the OSCE Minsk Group — France, Russia and the United States — have urged the sides to cease fire and resume dialogue without preconditions. Turkey, in turn, has pledged its full support for Azerbaijan.
Baku launched an offensive to prevent the separation but ended up losing control over the breakaway enclave during the 1992-1994 war. The OSCE Minsk Group had mediated the peace process since 1992 and achieved a ceasefire agreement in 1994.
As Azerbaijan refused to recognise Nagorno-Karabakh as a party to negotiations, the latter's interests were being represented by Armenia.