The interim government in Libya has ordered troops to use all necessary force to end nearly a week of fighting between rival militias in the west of the country.
At least 16 people have been killed and 89 injured in the clashes, which broke out again on Monday.
Security officials said fighters from the town of Zintan, who played a big role in ousting Colonel Muammar Gaddafi last year, are pitted against members of the El-Mashashia tribe, who did not join the rebellion.
Old feuds have re-surfaced since Gaddafi was overthrown.
Resentment between the two groups spilled over into fighting in December, when at least four people were killed, and erupted again on Monday when a Zintan fighter was shot and killed.
Heavy fighting continued on Saturday, resulting in many casualties.
The BBC reports the interim government has declared a military zone in the region and ordered the army to impose a ceasefire. Use of force has been authorised if the ceasefire is not respected.
