The head of an oil workers union in Libya was released Thursday, after being held by security officials for nearly a month. The union leader was held for a “routine interrogation.” A week ago, the oil firm NOC, requested that he be released. The oil firm is based in Tripoli, which is still controlled by the country’s government.
See "Eastern Libyan forces release head of oil workers union", Ayman al-Warfalli & Ahmed Elumami, Reuters, May 31, 2019