The United Nations’ high commissioner for human rights Michelle Bachelet said Monday that artillery strikes in the disputed region of Nagorno-Karabakh could amount to war crimes.

Bachelet said that, despite a deal reached last Friday by Armenia and Azerbaijan to from targeting civilians, artillery salvoes against populated areas were reported over the weekend.

“Instead, homes have been destroyed, streets reduced to rubble, and people forced to flee or seek safety in basements. Such attacks must stop and those responsible for carrying them out, or ordering them, must be held to account”, Bachelet said, adding that it could also be a war crime under the Geneva Conventions.

Armenia and Azerbaijan were part of the Soviet Union and have been involved in a territorial conflict since gaining independence within the 1990s. The main issue is the disputed Nagorno-Karabakh region, internationally recognised as part of Azerbaijan but controlled by ethnic Armenians. At least 1,000 people have died since the fighting began on September 27, including many civilians.

Bachelet added that about 40,000 Azeris had been temporarily displaced by the latest fighting while some 90,000 ethnic Armenians had fled Nagorno-Karabakh and were currently in Armenia.

Meanwhile, Armenia’s prime minister called for an investigation into the presence of “foreign mercenaries” in Nagorno-Karabakh after ethnic Armenian forces said they had captured two fighters from Syria. Azerbaijan denied the presence of foreign fighters.