Azerbaijan accused Armenia of killing 21 people and wounding dozens in a missile strike near Nagorno-Karabakh on Wednesday, the deadliest reported attack on civilians in a month of fighting over the disputed region.

Armenia immediately denied carrying out the attack, the second in two days that Azerbaijan says killed civilians in the Barda district close to the frontline.

Yerevan also accused Azerbaijani forces of deadly new strikes on civilian areas of Karabakh, as both sides claim the other is targeting civilians after weeks of fierce frontline clashes.

The latest attacks came despite a US-brokered truce agreed at the weekend, the third ceasefire attempt in a row to collapse just minutes after it took effect.