The European Union has added to its Libya sanctions list 26 energy firms.
Speaking after an EU foreign ministers meeting in Luxembourg, German Foreign Minister Guido Westerwelle said the move amounted to a de facto oil and gas embargo.
The 27-nation bloc had already imposed an arms embargo against Libya after Muammar Gaddafi used violent means to put down antigovernment protests that erupted in mid-February.
Travel bans and assets freezes were also enforced against Gaddafi and his associates.
The assets and financial transactions of several financial entities were frozen.
Libya produces some 1.7 million barrels per day and exports 1.49 million in normal times, most of it to Europe.