Both sides said there had been intermittent clashes overnight and today as well, accusing each other of using heavy weapons, tanks and artillery and of pulling the trigger first.
"Armenian armed forces violated the ceasefire 130 times during the night. They were shooting from mortars, grenade launchers, and large-calibre machine guns," Azerbaijan's defence ministry said in a statement.
"The shelling was carried out from both Armenian territory and from Armenian-occupied Karabakh," the statement said. "The Azerbaijani army returned fire."
"Azerbaijanis are attempting to attack but are being repelled," he said. "The situation is tense, but there is no panic."
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The Armenian-backed rebel defence ministry in Karabakh meanwhile said that "Azerbaijan renewed shelling its positions this morning from rocket-propelled artillery and tanks."
Fierce clashes left at least 18 Armenian and 12 Azerbaijani soldiers dead yesterday and reportedly claimed the lives of two civilians after both sides accused each other of attacking with heavy weaponry across the volatile frontline.
Armenia's President Serzh Sarkisian called the clashes the "largest-scale hostilities" since a 1994 truce ended a war in which Armenian-backed fighters seized the territory from Azerbaijan.
Both Russia and the West appealed to all sides to show restraint, with key regional power broker President Vladimir Putin calling for an "immediate ceasefire".
US Secretary of State John Kerry urged the arch foes to return to peace talks under the auspices of the Organisation for Security and Cooperation in Europe (OSCE), reiterating "there is no military solution to the conflict".
Turkish President Recep Tayyip Erdogan meanwhile vowed to back traditional ally Azerbaijan "to the end" in the conflict.