Supporters of a federal system in Libya ransacked offices of the electoral commission in the eastern city of Benghazi on Sunday in protest at next's week nationwide vote, witnesses said.

"A group of people entered the commission's office, ransacked the place and destroyed whatever was inside the building," said Jamal Boukrin, the commission's chief for Benghazi.

An AFP photographer said the assailants, shouting slogans calling for a "fair distribution of seats" in the General National Congress, did not attack commission employees but destroyed everything in their path.

A leader of the movement, Abdeljawad al-Badin, told AFP the violence was in protest at their demands for eastern and western Libya to be allocated an equal number of seats being ignored by the authorities.

Leaders of the autonomy movement for eastern Libya have called for a boycott of the July 7 vote.