By Ahmed Elumami
TRIPOLI (Reuters) - Libyan armed brigades allied with rival political leaders in Tripoli have exchanged sporadic gunfire and set up checkpoints in areas they control, challenging the authority of the United Nations-backed government.
Opponents of the U.N.-supported Government of National Unity (GNA) defied it on Friday by taking over a parliamentary building and demanding a new government, triggering a standoff among rival brigades operating in the city.
Since a 2011 uprising toppled autocrat Muammar Gaddafi, Libya has fallen into factional fighting among battalions of former rebels who have turned against one another, backing competing political leaders in a struggle for control.
Amid the chaos, oil production has been slashed in the OPEC member state, and people-smugglers and Islamic State militants have been able to expand their operations, a source of concern for Europe and the United States.
The GNA arrived in Tripoli in March as part of Western efforts to end Libya's instability after competing factions operated two rival governments in Tripoli and the east. But it has struggled to extend its influence over hardliners.
On Friday, leaders from the old Tripoli government, including former premier Khalifa Ghwail, and their armed brigades took over a parliament office in the Rixos Hotel that was supposed to provide offices for the State Council, one of the legislative bodies in the new unity government agreement.
Heavy gunfire rattled the capital on Saturday and Sunday and new checkpoints quickly appeared, including west of Tripoli near the Sooq Toulata area as rival brigades positioned themselves, witnesses said. Brigades have been more heavily armed than usual around the capital.
"What has happened is unfortunate and disgusting. It is an individual cause that represents no group," said Fathi Bashagha, security coordinator with pro-government forces, referring to the takeover of the building.
"We did not see any city, municipality, or political party supporting this desperate attempt."
In front of the Rixos Hotel, armed brigades loyal to the former parliament and Ghwail were stationed along with armored military vehicles. Traffic has been flowing normally in the city, though shops around the Rixos were closed.
Sporadic clashes broke out at the weekend between two armed groups in Tripoli's Zawiyat Dahmani district, but no one was hurt. Shooting was heard all over the city during the evenings.
On Monday, Tripoli was calm with businesses and shops operating as usual in the city centre.
Tripoli is controlled by a patchwork of rival armed groups, some of whom who are assigned to interior or defense ministries in a quasi-official role. Some are Islamist-leaning, others allied with cities outside the capital.
With no national army, these brigades are key power brokers. Armed battalions have often stormed ministries, government offices and even parliament to exert political pressure or demand higher salaries.
(Writing by Patrick Markey; Editing by Mark Trevelyan)