Factbox: Nagorno-Karabakh - old tensions erupt again into violence

(Reuters) - Nagorno-Karabakh is a mountainous and heavily-forested patch of land that sits inside the territory of ex-Soviet Azerbaijan.

Under international law, Nagorno-Karabakh is recognised as part of Azerbaijan. But the ethnic Armenians who make up the vast majority of the population reject Azeri rule. They have been running their own affairs, with support from Armenia, since Azerbaijan's troops were pushed out in a war in the 1990s.