EUROPE and Asia have joined forces to increase pressure on the US to drop its protectionist steel tariffs or face the consequences.

A united front is threatening billions of pounds of retaliation against products ranging from oranges to Harley-Davidson motorcycles unless the US backs down.

The call for change in US trade policy followed a ruling by the World Trade Organisation (WTO) that the duties were illegal.

"As frank and loyal friends of the United States, we hope that Washington will remove as soon as possible the steel tariffs that are considered illegal by the WTO," said Adolfo Urso, Italy's Industry Ministry under-secretary in charge of foreign trade.

"We want to ward off a commercial war that, for its size, would be unprecedented."

The US insisted it was right to impose what it described as safeguard tariffs for three years to give its steel industry time to restructure.

EU officials said they will act if the steel duties are still in place five days after the report has been formally adopted by the WTO, which is likely to take place on December 1.