At least 16 people have been killed in heavy fighting in the Libyan city of Benghazi between forces allied with the official government and Islamic State fighters, a military commander said on Wednesday.

Benghazi, caught up in fighting for more than a year, is just one front in Libya's multi-sided war involving two competing governments -- an official one in the east and a self-declared one controlling Tripoli -- and the loose coalitions of armed factions backing them.