Armenia has accused Azerbaijan of violating a recent humanitarian ceasefire in the disputed Nagorno-Karabakh region.
The ceasefire had only been in effect for a moment before Armenia made its accusations on Twitter.
The ceasefire took effect at midnight local time on the night between Saturday and Sunday.
A spokesman for the Armenian Ministry of Defense claims Azerbaijan started an artillery fire in Nagorno-Karabakh as early as four minutes after midnight and fired artillery fire for nearly three hours.
In addition, Azerbaijan allegedly firing rockets for about half an hour.
Azerbaijan has not yet responded to the allegations against Armenia.
Nearly three weeks of fighting
The countries have been fighting for almost three weeks over the disputed Nagorno-Karabakh region.
According to official, albeit incomplete, more than 700 people have died in the fighting.
The announcement of a humanitarian ceasefire came after Russian Foreign Minister Sergei Lavrov had spoken on the phone with the foreign ministers of Armenia and Azerbaijan.
According to the Russian Foreign Ministry, Lavrov had stressed the "need to adhere strictly" to the ceasefire agreement agreed in Moscow a week ago.
The ministry also said foreign ministers had assured that it was important to start "real" talks to resolve the Nagorno-Karabakh conflict.
Attacks on civilians
Before declaring a ceasefire, both countries reported on hostilities against their civilians.
On Saturday, Azerbaijani President Ilham Aliyev threatened to retaliate against Armenia in the morning for a missile strike on the city of Ganja.
According to the Azerbaijan Public Prosecutor's Office, 12 civilians were killed and at least 40 people were injured in the attack.
Aliyev described the attack as a "war crime."
He also said Azerbaijan would conquer Nagorno-Karabakh by driving Armenian troops away "like dogs."
The attack destroyed several residential buildings in Ganja, a population of 300,000, which was also hit by a missile six days ago.
At that time, ten civilians died.
Earlier, the Azerbaijani army had fired artillery fire at the controversial town of Stepanakert in Nagorno-Karabakh.
According to Armenpress, the national news agency of Armenia, civilians were wounded in the nearby village of Shoshi.
Armenpress also said that unmanned aircraft from the Azerbaijani army destroyed military buildings on the Armenian side and also damaged civilian infrastructure.