TOKYO (Bloomberg) — Mitsui O.S.K. Lines Ltd., operator of the world's largest merchant fleet, more than doubled its full-year profit forecast as a global economic rebound revives dry-bulk and container-shipping rates.

The company expects net income of five billion yen ($56 million) in the year ending March, compared with a previous forecast of two billion yen, it said in a statement. Kawasaki Kisen Kaisha Ltd., Japan's No. 3 shipping line, pared its loss forecast to 70 billion yen from 79 billion yen.

Mitsui O.S.K. said "strong demand" in China for coal and iron-ore shipments would support bulk-shipping rates, while oil-tanker fees may climb on the scrapping of single-hull vessels and higher demand for petroleum. Container rates are also rising as lines park ships, end price wars and see a rebound in demand for shipments to the US and Europe amid an economic revival.

"We're getting a lot of indicators that the fourth quarter is doing well, especially for containers," said Janet Lewis, an analyst at Macquarie Capital Securities (Japan) Ltd. "Shipping lines' success in withholding supply along with an increase in demand for imports helped profits" in the three months ended December.

Nippon Yusen K.K., Japan's largest shipping line by sales, widened it loss forecast for the year to 29 billion yen from 27 billion yen, citing "harsh times" at its cruise-liner business and losses at an air-cargo unit.

Separately, Nippon Yusen said it may delay plans to merge its air-freight business with Japan Airlines Corp.'s cargo unit in April because the two sides haven't agreed on the terms of the deal. Negotiations are continuing, the two companies said.

Mitsui O.S.K.'s current profit will probably increase to 70 billion yen next fiscal year, Shugo Aoto, an executive officer at the shipping line, told reporters in Tokyo. The company is predicting 13 billion yen this year.