The World Trade Organisation (WTO) has upheld a judgment made against the USA, which found that their mandatory country of origin labels for meat and pork discriminate against meat and livestock imports.

Canada and Mexico, two of the USA's biggest trading partners, brought the challenge against the country, saying that US labelling laws, which require details on where an animal is born, reared and slaughtered, unfairly discriminate against their livestock exports.

The WTO concluded the US law "necessitates increased segregation of meat and livestock according to origin... and increases the incentive to choose domestic livestock over imported livestock."

According to the EU Commission, Canada claims the US rules cost its farms and processors $1 billion (€0.9 billion) a year in lost sales and lower prices since the law was introduced in 2009.

Washington tweaked the rules after a judgment in 2011, but Ottowa and Mexico City insisted the US had not done enough.

In December 2014 the EU extended country of origin labels - already in place for beef - to fresh pork, chicken, sheep and goat meat.