At least 10 people were killed in skirmishes between Azeri government forces and ethnic Armenian separatists controlling the breakaway Nagorno-Karabakh enclave of Azerbaijan, officials from both sides said on Friday, Reuters reported.

The recurring violence around Nagorno-Karabakh, a mountainous majority Armenian area, underlined the risk of broader conflict in the South Caucasus where vital oil andnatural gas flow from the Caspian region to Europe.

Energy-producing Azerbaijan, host to oil majors including BP, Chevron and ExxonMobil, frequently threatens to take Nagorno-Karabakh back by force, and is spending heavily on its armed forces.

Armenia, an ex-Soviet republic and an ally of Moscow, has warned it would intervene if Nagorno-Karabakh were overrun.

Fighting between ethnic Azeris and Armenians first erupted in 1991 and a ceasefire was called in 1994. But Azerbaijan and Armenia have regularly traded accusations of further violence around Nagorno-Karabakh and along the Azeri-Armenian border.

Azerbaijan's Defence Ministry said eight of its soldiers were killed in overnight skirmishes along the line that demarcates Nagorno-Karabakh from Azerbaijan.

"The Armenian army made several attempts to break through Azerbaijan's line of defence ... The blood of our soldiers won't go unavenged," the Azeri ministry said in a statement.

The breakaway enclave also said two of its combatants were killed in the fighting, adding that one more had been killed and two wounded in a clash earlier this week.

Bakudaily.az