Libya's deputy minister of industry was shot dead during a visit to his hometown of Sirte, east of Tripoli, on Saturday, Al-Jazeera reported.
Hassan al-Droui, a former member of Libya's National Transitional Council, was killed near a market in central Sirte after evening prayers, the report said, citing the Libya Herald.
"Hassan al-Droui, the deputy minister for industry, was killed by unknown attackers overnight, during a visit to his native city of Sirte," a security official told the AFP news agency.
Libya has been plagued with unrest since the rebellion which ended with the ouster of former President Muammar Qaddafi.
On Saturday, fighting between rival tribes in southern Libya killed 19 people and wounded another 20, reported Al-Jazeera.
"Violent confrontations broke out between Toubous and Awled Sleiman early this morning," Ayoub al-Zarrouk, chief of the local council in Sebha told AFP, naming the tribes involved.
Local sources said the clashes were sparked by the death on Thursday of a militia chief linked to Awled Sleiman, adding that the tribe accused the Toubous of murdering him.
Saturday's fighting is the worst between the tribes since they struck a cease-fire agreement in March 2012 following deadly battles that killed at least 150 people and wounded 400 others.
Since Qaddafi’s ouster, the government in Libya has struggled to contain militias in control of parts of the country. The militias took part in the uprising that led Qaddafi’s fall in 2011 but have been told by the interim government to disband or join the army by the end of the year.
Two years after the fall of Qaddafi, independent militias still control large part of the North African country and regularly fight each other.
The heavy violence in Libya, especially in the capital Tripoli, led to a United States announcement that it would train up to 7,000 members of Libya's security and special operations forces.