TRIPOLI, June 15 -- Remnants of terrorist groups on Thursday carried out a new attack on the oil crescent region in Libya and clashed with the forces of the eastern-based army, posing a new military escalation in a vital location that contain major oil fields and ports.

The army two years ago defeated and expelled the former chief of the oil installations guards, Ibrahim Jathran, and the terrorists he allied with from the region they occupied, after they stopped oil exports for years and caused huge losses.

"The attack on the vital targets of the oil sector is catastrophic and ill-timed, in light of the political rapprochement between the Libyan parties towards ending the dispute and moving towards elections," said Ali Sweih, member of the Higher Council of State.

He called on the eastern-based House of Representatives to resolve the issue quickly and unite efforts with the Higher Council of State to end the current crisis.

"There are Libyan and international parties that instructed Jathran to carry out this attack ... It comes when the Central Bank's foreign exchange reserves began to increase due to the increase of oil production and the recovery from the losses during the past several years," Sweih told Xinhua.

He also stressed the need to capture Jathran, wanted globally, and called for unity by all parties to facilitate handing him over.

The clashes between killed 5 soldiers when the terrorists attempted to progress towards the region, before they were defeated and expelled by the army, the army said.

The oil crescent region is located some 500 km east of the capital Tripoli. It contains the country's largest oil ports.

"The military forces securing the oil fields and ports, during the past few weeks, had received information about military buildup of terrorists in Sirte desert near the oil crescent. The air force then carried out airstrikes targeting vehicles and individuals in the area," retired army Brigadier, Ahmed al-Hesnawi, told Xinhua.

"A preemptive operation should have been launched before the terrorists reached oil sites. The option of attack is better than defense, even if the army leadership was certain that the terrorists do not have a great ability to advance towards those sites," al-Hesnawi said.

The Libyan air force carried out three airstrikes on Tuesday, targeting terrorists south of the city of Sirte, after monitoring the presence of al-Qaida terrorists fleeing Benghazi and mercenaries from Africa, army spokesman said.

In a televised statement, Jathran confirmed that the attack is "a battle to lift the injustice of the people of the oil crescent, and not a battle for a personal, tribal, regional, or partisan purpose."

"The oil will never be a bargaining chip to the conflicting parties," Jathran said, pointing out that the oil supplies "will continue uninterrupted under supervision of the National Oil Corporation."

Jathran faces charges of damaging state institutions and wasting of public funds after closing oilfields and ports in July 2013, causing losses of over 100 billion dollars.

The terrorists allied with Jathran are remnants of the group called Benghazi Defense Brigades, an extremist group that fought and lost against the army in Benghazi last year.

They launched several attacks in the oil crescent region and some eastern cities. The army accuses the group of recruiting mercenaries from Africa.

The deadliest attack carried out by the group was on the southern air base of Brak in May last year, which killed 141 army soldiers.

After they were defeated and expelled last year from Jufra town, some 240 km south of Sirte, the extremists fled towards valleys and desert areas.

The Libyan House of Representatives condemned the terrorist attack on the oil crescent, considering it an attempt to strike the security and stability of the region and to disrupt the main source of income in the country.

The UN-backed Prime Minister Fayez Serraj also condemned the terrorist attack, calling it an "irresponsible escalation pushes the country into civil war that the Libyans strive to avoid."

The UN Mission in Libya warned that "this dangerous escalation puts Libya's economy in jeopardy and risks igniting a widespread confrontation."

Hours after the attack, the state-owned National Oil Corporation declared state of force majeure at Es Sider and Ras Lanuf oil ports in the region, and also evacuated all its employees there for security reasons.

The corporation also said the attack caused losses of 240,000 barrels of oil, almost a quarter of Libya's daily oil production.