Clashes in a western Libyan city left six dead and at least 20 injured, a government spokesman said.

Nasser al-Manei said unidentified assailants attacked an airport and a hospital in Ghadamis near the Algerian border, some 280 miles south west of the capital Tripoli.

He said the attackers came from outside the city. Government forces were deployed to the city to stop the fighting, Mr al-Manei said.

He did not say what caused the violence, but clashes have been common throughout the country since last year's overthrow of dictator Muammar Gaddafi.

They have sometimes pitted rival members of the former rebel militias that fought his regime against each other.

Other conflicts have involved ethnic groups with grievances dating back to his time in power.

Ghadamis is inhabited by Berbers, an ethnic group who occupy most of the country's western desert mountains and who were long suppressed by Gaddafi.

The ruling National Transitional Council has struggled to impose its authority over the country since Gaddafi was killed and his loyalists' strongholds fell in October 2011.

In February, tribal strife left more than 100 people dead in the southern Libyan region of Kufra near the Chadian border.

It pitted an Arab tribe against the Tabu, an African group who are some of the original inhabitants of south Libya.

The Tabu like the Berbers were heavily suppressed under Gaddafi.

Fighting in another southern desert region, Sabha, left 147 people dead in March.