The WTO's Appellate Body ruled on Monday that the US Congress failed to change cotton policies enough to comply with rulings that some of those policies violated international trade treaties.

The final loss before the WTO's highest court moved the winning litigant Brazil into a position to request authority to impose massive trade sanctions against American goods and services.

In the past the level of sanctions has been estimated to be worth up to $US4 billion a year, among the largest ever permitted by the WTO.

Brazilian officials said they expect to request the sanctions, since it seems unlikely that the US government will make the required changes.

Roberto Azevedo, the top trade official at Brazil's Foreign Ministry, said: "We're going to ask for the authorization to retaliate.

"The only alternative is if the United States takes steps to fully comply with the WTO ruling, but this is an unlikely scenario."

Mr Azevedo did not spell out what amount of sanctions Brazil will be seeking.

Often arbitrators award smaller penalties then requested.

"We're clearly disappointed with the findings that came out of the WTO," says Sean Spicer of the US Trade Representatives Office.

"We believe that the changes that were made by the United States to bring the challenge payments and guarantees into compliance with the WTO's recommendations did just that."

The US can take the matter to arbitration before a WTO dispute panel, according to Mr Spicer.

He says the prices the WTO looked at differed from current market prices.

"So the US is not and has not been making payments tied to cotton production," Mr Spicer says.

"There is no basis to say US payments are having any impact on cotton prices."