LONDON (Bloomberg) — Bermuda-based Frontline Ltd., the world's largest operator of supertankers by capacity, ordered four of the vessels from China's Zhoushan Jinhaiwan Shipyard Co. Ltd.

The carriers will be delivered between June and December of 2011 and each will have a carrying capacity of about 320,000 deadweight tons, Frontline said in a statement distributed yesterday by Hugin. The shipping line also purchased options to have two extra vessels of the same size built.