|Fighting in Bani Walid has forced many residents to flee while more NTC troops filed in [David Poort/Al Jazeera]
Forces loyal to Muammar Gaddafi have killed at least 15 guards and injured two others in an attack on an oil facility outside the coastal town of Ras Lanuf, fighters of Libya's National Transitional Council (NTC) have said.
Citing NTC fighters present at the scene, Al Jazeera's Hoda Abdel-Hamid said a column of vehicles carrying armed Gaddafi loyalists drove up to the refinery's checkpoint on Monday morning.
Ras Lanuf is located approximately 600km east of the capital, Tripoli.
The attack came as pro-and anti-Gaddafi forces fought fierce battles around Sirte and Bani Walid, key towns still controlled by forces of the toppled leader.
Anti-Gaddafi fighters had reached the gates of Bani Walid, located 150km southeast of Tripoli, on Sunday but encountered fierce resistance from Gaddafi loyalists who ignored a NTC deadline to surrender.
Supporters of the toppled regime continued to fight for Gaddafi a day after Saadi Gaddafi, son of the ousted leader, fled to Libya's southern neighbour Niger.
NTC troops told Al Jazeera that residents were fleeing the desert town as fighting raged with NATO fighter jets circling overhead.
NTC fighters, however, said they had advanced towards Sirte despite tougher than expected resistance from Gaddafi loyalists.
The NTC has said that it will not declare Libya "liberated" until it has taken control of towns still in the hands of Gaddafi loyalists.
Meanwhile, Mahmoud Jibril, Libya's de facto prime minister, has said that oil production in some oil fields have been normalised following months of unrest.
The announcement was made on Sunday as Jibril vowed to form a new government within 10 days, carrying representation from all parts of the country - including areas that are not yet under the new establishment’s control.
Libya faces serious challenges, especially on the security and stabilisation front, but some oil fields have already resumed production, he said, emphasising that salaries of government workers will be paid on time.
"The salaries of the month of July will be paid in the eastern part of Libya, following which the month of August will be paid along with a bonus," he said.
"The liberated parts of Libya will also receive salaries with bonuses.
"The liquidity issue has been taken care of since we received the first instalment (from the UK) of Libyan currency, which was previously frozen, an installment of over a billion dinars. There will be a second installment of 700 milion dinars coming."
Jibril declined to identify which fields were now back in use, citing security reasons.