Officials say four Filipinos are among nine foreigners abducted by still-unidentified armed men from an oil field in central Libya and their abductors have yet to communicate any demand.

Department of Foreign Affairs spokesman Charles Jose said Monday the Philippines is working with the Filipinos' employers, Austrian-owned VAOS Oil Service, the Libyan government and embassies of the others abducted.

Austria's Foreign Ministry believes the attackers are Islamic State-allied militants.

Friday's attack brings the total number of Filipinos missing in Libya to seven. Three others were abducted in another oil field on Feb. 3 and their whereabouts also remain unknown. Jose says the cases underscore escalating security threats to workers in oil fields there, and appealed to some 4,000 Filipinos in Libya to avail of the Philippines' mandatory repatriation program.