The violence and calls for boycotts threaten to tarnish the process of electing a 200-member assembly to form a government and oversee writing of a constitution.
In Benghazi, where the revolt that unseated long-time ruler Muammar Gaddafi began last year, Fadallah Haroun, commander of a former rebel militia, said he joined protesters in the attack on the election commission.
This came after the ruling transitional council in Tripoli turned down demands to give the east an equal share of seats in the assembly. He said that two other cities in eastern Libya have witnessed similar incidents.
As the situation stands now, Tripoli and western Libya would have 102 seats, while the oil-rich east's share would be 60. The rest would go to the sparsely populated south.
Eastern leaders charge this leaves them with no influence over drafting the constitution.
(Source: Belfast Telegraph)