GENEVA, Dec 2 (Reuters) - Brazil and Thailand have both launched trade disputes over a controversial U.S. method of tackling unfairly priced imports, documents on the World Trade Organisation (WTO) website show.

The moves mark a further challenge to Washington's use of "zeroing" in assessing duties on goods that are "dumped" or imported for less than they cost at home -- an approach which has been repeatedly condemned by the WTO's top court.

Brazil, the world's biggest orange juice exporter, is seeking consultations with the United States over U.S. anti-dumping measures on orange juice, it said in a filing to the WTO.

Brazil's foreign ministry said the U.S. authorities had calculated that Brazilian companies had dumped orange juice between August 2005 and February 2007 at margins of up to 4.81 percent below the fair price.

"The request for consultations questions the use of the practice known as 'zeroing' in reviews by the U.S. Commerce Department in anti-dumping investigations into Brazilian orange juice," it said in a statement.

"Brazil believes the dumping margins have been artificially inflated by being calculated using 'zeroing'," it said.

Orange juice futures prices are at a four-year low in New York and brokers say further losses are likely.

Thailand is seeking consultations over U.S. anti-dumping measures on plastic bags used for shopping, it said.

Global trade rules allow an importing country to impose anti-dumping duties on imports that are sold for less than they cost in their home country, if that damages businesses in the importing country.

To calculate or review those duties often requires comparing different batches of the product to work out an average.

In zeroing, the importing authorities ignore -- or treat as zero -- cases where the imported goods actually cost more than at home. All the WTO's 153 members except the United States object to the use of zeroing, which has already been the target of a dozen trade disputes.

But Washington says it should be allowed and that WTO courts that have rejected it have overstepped their powers. The United States is pushing to have zeroing explicitly recognised in a new global free trade deal under negotiation.

(Reporting by Jonathan Lynn; Editing by Charles Dick)

Reuters, Tuesday December 2 2008

Source: www.guardian.co.uk