By Ghaith Shennib and Ulf Laessing
TRIPOLI (Reuters) - Libyan militia fighters on the government payroll fought each other with rifles, grenades and anti-aircraft weapons on the streets of Tripoli on Tuesday in the worst clashes in the capital in weeks.
No one was killed, but the fighting underlined how Libya's government is finding it harder to contain former fighters and Islamist militants in a country awash with weapons two years after Muammar Gaddafi's fall.
Strikes and armed protests by militias and tribal gunmen demanding payments or political rights have shut much of the OPEC member's oil output for months and deprived the government of its key source of income.
Prime Minister Ali Zeidan has sought to co-opt militias that helped to topple Gaddafi by integrating them and their weapons from the NATO-backed revolt into the nascent army and police. But in practice, most continue to report to their commanders or tribes.
Tuesday's fighting broke out just after midnight in Tripoli's eastern Suq al-Juma district and a central coastal area, where a Reuters witness saw two burned out pick-ups belonging to a militia on the government payroll.
A senior security official said three people had been wounded, among them the head of a militia from the central city of Misrata who was critically wounded.
Shooting started after members of one militia paid by the government to help secure Tripoli stopped a car without plates and detained the driver, the official said. He was brought to a security office in Suq al-Juma but later released after he proved the car belonged to him.
Angered about the detention, the car owner returned with members of a rival militia, who came back to the checkpoint in four to five cars. An ensuing exchange of gunfire spread to other parts of Tripoli.
Reuters reporters could hear rocket-propelled grenades and heavy anti-aircraft guns being fired throughout the night. The situation calmed down after daybreak, though occasional rifle shots could still be heard in the morning.
Fighting between militias is often about personal arguments, control of local areas, stolen cars or smuggled goods such as drugs or alcohol that are banned in Libya.
Tripoli has largely been spared the assassinations and bombings that happen almost daily in the eastern city of Benghazi, but security in the capital remains fragile.
Several embassies have been attacked, and last month a group of former rebels briefly kidnapped Zeidan from a Tripoli hotel before other militiamen freed him hours later.
Dozens of people demonstrated and burned tires on Monday night in Benghazi in protest against the deteriorating security situation after the recent killing of an intelligence officer and his young daughter in a bomb attack, residents said.
Many people in eastern Libya and its main city, Benghazi, demand autonomy from Tripoli and a greater share of oil wealth, accusing Zeidan's government for abandoning their region.
On Sunday, an autonomy movement launched a shadow government for the east, a move that changes little on the ground but will worsen ties with the weak central government.
(Reporting by Ghaith Shennib and Ulf Laessing; Editing by Patrick Markey and Kevin Liffey)