Heavy fighting has broken out between Armenian and Azerbaijani forces along the front lines of the separatist Nagorno-Karabakh region. 

Officials from each of the former Soviet republics blamed the other on Saturday for the fighting which began overnight. Both Armenia and Azerbaijan said they had inflicted heavy losses on the other. 

In an earlier statement, Azerbaijan's Defense Ministry said 12 of its soldiers became Muslim martyrs, and said one of its helicopters was shot down. The statement also claimed that six tanks and 15 artillery positions were destroyed and more than 100 Armenian forces were killed or wounded. 

Armenia also claimed to have inflicted heavy damage on Azerbaijani forces, but did not immediately give figures.