Brazilian mining giant Companhia do Vale do Rio Doce (CVRD) said Wednesday it had signed a 25-year freight contract with Bergensen Worldwide (B.W. Bulk) involving the construction of the four largest bulk cargo ships ever made.

B.W. Bulk is the world's largest owner of bulk cargo ships and provides services for the steel and iron ore industries.

The ships will have a capacity of 388,000 tons (dwt) each and are part of CVRD's strategy to develop an exclusive transport system for iron ore between Brazil and China, the company said in a statement.

""The first of these ships should go into operation in the first half of 2011, contributing to the reduction of cost through economies of scale and minimizing C+F (cost plus sea freight) price volatility of our iron ore to China," said the Brazilian company.

The largest bulk cargo ship in operation, with a 364,000 ton capacity, was introduced by CVRD, in partnership with B.W.Bulk in 1986.

B.W will also convert an oil ship for CVRD and this is expected to be ready to operate in 2008.

CVRD also said that it had signed a second contract, lasting 20 years, with Nippon Yusen Kaisha (NYK) Japan, involving the construction of a ship with a 300,000 ton capacity (dwt), the delivery of which is scheduled for 2011.