BENGHAZI, Libya (Reuters) - Eastern Libyan forces loyal to military commander Khalifa Haftar fought tribesmen for a second day for control of the southern city of Murzuq, military officials and residents said, as part of campaign to secure oilfields in the south.

At least three soldiers have been killed since Haftar’s Libyan National Army (LNA) force on Wednesday entered Murzuq, a city 900 km (560 miles) south of the capital Tripoli, a military source said.

Around 11 tribesmen have been killed and 15 wounded, Libya’s al-Ahrar channel said. Reuters could not independently confirm the report.

It was the first protracted city battle fought by the LNA since it started a campaign to control the south and its oilfields a month ago.

Haftar, whose powerbase is the eastern city of Benghazi, leads the LNA, which controls the east of the North African nation and major oil ports in the region. Haftar has become a major player in Libya since his forces seized Benghazi in 2017, after a three-year battle mainly with Islamist fighters.

So far the LNA had mostly negotiated access with local groups and tribes, securing the leading city of Sabha and the El Sharara oilfield without facing resistance.

Murzuq is important to the LNA because it is key to securing the 315,000 barrels a day-El Sharara, lying between the field and Sabha, home to the LNA’s main southern base.

Last week, the LNA sent troops to control the field but they had set off from a smaller base in Ubari, a city northwest of Murzuq. The LNA has gained access to El-Sharara field by working with state guards who had closed it in December to back financial and other demands. NOC declared has force majeure, a waiver on its contracts, since then.

State oil firm NOC, based in Tripoli, in the west of Libya where the internationally recognised government is based, has said it will not reopen the field without a new security arrangement and once other conditions are met, such as ensuring its workers are safe.

Haftar’s LNA is allied to a parallel administration based in the east, and it is locked in a conflict with rival forces over control of the OPEC member country.