In Paris, French Prime Minister Manuel Valls said the situation in the North African country will be "the big issue in the coming months", noting how "terrorism constantly mutates".
ISIS, which already controls large swathes of territory in Iraq and Syria, has exploited the chaos that spread across Libya after veteran dictator Moamer Kadhafi was toppled and killed in a 2011 uprising.
The terrorists control the oil hub of Sirte, Kadhafi's hometown 450 kilometers (280 miles) east of Tripoli and have been battling both government forces and terrorists in second city Benghazi, a further 550 kilometres to the east.
Another reports reveal ISIS using flight simulators to train pilots in Sirte. They are learning to fly planes using at least one flight simulator to help them advancing easily to other Libyan areas, according to military officials in the strategically situated North African state.
ISIS now trying to expand their zone of influence to Ajdabiya, which lies between Sirte and Benghazi and is in the heart of one of the North African country's major oil-producing regions.
They are also trying to retake the city of Derna, in the country's far east, have having been driven out by rival forces.
In New York, UN experts agreed in a report issued on Tuesday that ISIS is struggling to expand its foothold in Libya with no more than 2,000 to 3,000 fighters in the North African country.
"The senior officer said warplanes Tuesday struck a house in an industrial area south of Ajdabiya where terrorists were meeting."
The attack was part of a campaign aimed at preventing them from capturing the city, which is held by militias loyal to the recognized government.
Tuesday's strike was preceded by others last week, the officer said.
Last month, Foreign Minister Mohammed Dayri warned that Ajdabiya was at risk of becoming a "new fief" of ISIS, which has reportedly murdered 37 people, mostly military personnel, there in recent weeks.
Despite attacks on oil installations in Libya, the terrorists group lacks the capacity to seize, hold and manage oil fields or refineries in the country, the report said.
The ISIS terrorist group first appeared in Libya in 2014 when a group of Libyan ISIS fighters returned from Syria and reorganized in the port city of Derna, declaring eastern Libya to be a province of the caliphate.
A separate group gained control of Sirte in February 2015 but several months later, in June, ISIS was pushed out of Derna during fighting with other Islamist factions.
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