(Repeats to widen distribution, no change to headline or text)
* Vale declines comment on permission to dock in China
* Cargo on largest bulk carrier was bound for Dalian port
* Ship carries enough ore for 3.5 Golden Gate briges (Recasts, adds ship's position, scale of ore aboard vessel and shipping costs)
RIO DE JANEIRO, June 21 (Reuters) - Brazilian mining giant Vale VALE5.SA said on Tuesday it rerouted 391,000 tonnes of iron ore, its first cargo aboard a new class of giant bulk carriers, to Italy from its original destination of China.
The cargo is being shipped aboard the Singapore-flagged Vale Brasil, the world's largest dry-bulk vessel, a ship designed to reduce the cost of shipping the main steel ingredient to China -- the company's biggest market.
"The alteration (of the destination) is part of the flexibility in Vale's integrated logistics policy that allows Vale to reallocate the destination of exports, based on the needs of the market," the company said in an emailed statement.
Earlier this year Vale said it had not received permission for its so-called "Chinamax" or "Valemax" vessels to enter Chinese ports fully loaded.
When asked whether Chinese authorities had blocked Vale Brasil from entering the port of Dalian, a company spokeswoman declined to comment.
However, the statement said "Vale's expectation is that Vale China, the first vessel of the Valemax class totally produced in China and financed by Chinese financial institutions, will have a Chinese port as its first destination."
The iron ore aboard the Vale Brasil can be used to make about 261,000 tonnes of steel, or nearly three and a half times the amount used to build San Francisco's Golden Gate bridge.
Vale has commissioned 30 of these ships, to be delivered through 2013. All are larger than the previous largest bulk-carrier record holder, the 365,000-tonne MS Berge Stahl.
The fleet is expected to drive world freight rates lower as the new vessels add transport capacity to a market that has already seen a rapid increase in ships and ship size.
In the past year the Baltic Exchange Dry Bulk index .BADI, a measure of dry-bulk shipping costs around the world, has plunged 45 percent.
Vale faces increasing competition in China from Australian miners. While Australian ore generally has less iron content than Brazilian ore, it is mined closer to the China, the world's largest iron-ore market and steelmaker.
As of June 20, the cost of shipping ore to China from Vale's port of Tubarao in Brazil was $19.75 a tonne, according to the Metal Bulletin Web site, or more than double the $7.75 it cost to ship ore from Australia's port of Dampier.
As of late Monday, the Vale Brasil was steaming southwest along the South African coast near Durban, on course to re-round the Cape of Good Hope and re-enter the Atlantic Ocean, according to MarineTraffic.com.
(Reporting by Brian Ellsworth and Jeb Blount, additional reporting by Silvia Antonioli and Jonathan Saul in London; Editing by David Gregorio and Sofina Mirza-Reid)