Tugs moved the damaged Vale Beijing, the world's largest iron-ore carrier, from its berth in Brazil for repairs, opening space for other ships at a port responsible for about 10 percent of global iron ore exports.

Tugs moved the massive ship at mid-morning from the dock at the Port of Ponta da Madeira, outside the city of Sao Luis in northeastern Brazil. They will tow it outside the shipping channel for repairs, Brazilian Navy Commander Calmon Bahia, Harbormaster for Sao Luis, told Reuters by telephone.

The ship, delivered in September to its owner and operator, South Korea's STX Pan Ocean, is longer and wider than three soccer fields. It was on its first fully loaded voyage, a planned run to Rotterdam.

The Ponta da Madeira port is operated by Brazil-based Vale, the world's second-largest mining company, which has a long-term contract with STX to ship iron ore, the main ingredient in steel.

The Vale Beijing is one of the first of nearly three dozen very large ore carriers, (VLOC) or Valemax vessels that the company has commissioned to be built in China and Korea to help cut the cost of shipping iron ore to China, the world's largest steelmaker, and to clients in Europe.

While Vale's iron ore quality is higher, its distance from China puts it at a disadvantage to producers such as BHP Billiton and Rio Tinto. China has not yet granted Vale the right to dock its giant ships at Chinese ports, citing technical and potential environmental problems.

China and Brazil are trading partners but also commercial rivals. Beijing is concerned about its growing dependence on natural resources while Brasilia frets about the impact of Chinese manufactured goods on its own industries.

The Vale Beijing is loaded with 384,300 tonnes of high-grade ore, enough to make steel for nearly 3-1/2 Golden Gate Bridges. The ore was mined by Vale at its giant Carajas complex in Brazil's Amazon region and destined for Rotterdam.

Carajas is one of the world's largest sources of iron ore with more than 60 percent iron content and is connected to Ponta da Madeira by a railway that snakes nearly 900 km (560 miles) through the Amazon jungle, more than twice the distance between Washington and New York.

A crack in the Vale Beijing's ballast tanks was either the result of loading its holds or because of a structural problem, an official with the Sao Luis harbour pilots' service told Reuters on Tuesday.

The official, who asked not to be identified, said the Vale Beijing could not use its own motors during the move from the dock for fear of causing further damage.

Vale, based in Rio de Janeiro, said on Tuesday it had no new information on the ship.

Because there are no facilities to unload iron ore at Ponta da Madeira and no large shipyards in the area, repairs must be made by divers while the ship is at anchor, the harbour pilots' office said.

Ponta da Madeira is Brazil's No. 2 port by tonnage shipped after Vale's main iron ore terminal at Tubarao outside Vitoria, in the state of Espirito Santo.

Harbour pilots have detailed knowledge of the harbours where they live and work and are required by law and marine tradition to go aboard all large vessels arriving or leaving a port to steer them through approved channels and clear of marine obstacles and other ships.

Their work is closely regulated by world navies and coast guards and their dispatch offices track marine traffic and activity for the entire ports and harbours.

(Writing by Jeb Blount; Editing by Todd Benson, Sofina Mirza-Reid and David Gregorio)