Washington and its allies on Wednesday demanded that two key oil installations in the east of the country be returned to control of the UN-backed government in Tripoli, having fallen into the hands of a rival strongman.The oil ports at Ras Lanuf and Al-Sidra were seized from local militias last week by the breakaway military leader Khalifa Haftar, who said that all future revenues from the terminals under his control would be handed over to the unrecognized administration in the east of the country."Libya's oil facilities, production, and revenues belong to the Libyan people," said a joint statement by the United States, Britain, France and Italy. "These vital Libyan resources must remain under the exclusive control of the legitimate National Oil Corporation and the sole oversight of the Government of National Accord (GNA)."The statement came a day after Libya's UN-backed unity government called on the UN Security Council to block any "illegal" oil exports from the chaos-hit country after Haftar's force took the eastern terminals.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTER FOLLOW News24 Africa on Twitter and Facebook"Any attempts to circumvent the UN Security Council's Libya sanctions regime will cause deep harm to Libya's economy, exacerbate its humanitarian crisis, and undermine its broader stability," the statement by the five allies said."The international community will hold those who undermine Libya's peace, security, and stability to account," they warned.Libya has been wracked by conflict since the 2011 ouster and killing of longtime dictator Muammar Gaddafi in a Natoi-backed uprising, with rival governments and militias competing for authority and oil wealth.Haftar's self-styled Libyan National Army said on Monday it had regained "full control" of Libya's oil crescent, days after it retook Ras Lanuf and Al-Sidra from a rival militia in nearly two weeks of deadly clashes.The statement issued in Washington said the five western governments were "deeply concerned" about Haftar's move to hand over all revenue from the terminals to the eastern administration that he backs.