At least one person was killed and several injured in Tripoli on May 8 when former rebel fighters protesting outside the compound of the Libyan prime minister's office opened fire.
Witnesses and officials said fighters from Libya's western mountains came to the prime minister's residence to demand cash from the government.
Government spokesman Nasser El-Manee said one person from government security forces was killed.
Other witnesses said as many as four people may have been killed.
The prime minister's office is frequently the focus of protests by disgruntled militiamen demanding benefits in recognition of the role they played in last year's revolt to oust longtime ruler Muammar Qaddafi.
Libya plans next month to conduct its first free election to choose an assembly that would draft a new constitution.
Based on reporting by Reuters and AFP