STEPANAKERT, (Azerbaijan): A third attempt at halting weeks of fighting over Nagorno-Karabakh collapsed quickly on Monday with Armenia and Azerbaijan trading accusations of violating the US-brokered ceasefire within minutes.

As fighting over the disputed region enters its second month, international mediators are scrambling to bring a stop to frontline clashes and shelling of civilian areas that have left hundreds dead.

The latest "humanitarian ceasefire" was announced by Washington on Sunday, after truces brokered by Russia and France fell apart over previous weekends. It took less than an hour after the ceasefire was due to begin at 8:00 am (0400 GMT) for the first accusations to be made.

Azerbaijan's foreign ministry said Armenian forces had shelled the town of Terter and nearby villages in "gross violation" of the truce. Armenia's defence ministry said Azerbaijani forces had violated the truce with artillery fire on combat positions in various parts of the frontline. Karabakh's rights ombudsman said a missile strike had hit a village in the region, killing one civilian and wounding two others.

Azerbaijan and Armenia have been locked in a bitter conflict over Karabakh since Armenian separatists backed by Yerevan seized control of the mountainous province in a 1990s war that left 30,000 people dead.