US companies and trade associations are asking their European customers for help in getting apparel such as blue jeans and underwear removed from a list of products threatened by an additional 100 percent import duty.

Companies like Levi Strauss, Haggar Corp and Jockey International are among those being threatened with the tariffs by the European Union in retaliation for an illegal US tax break.

A 14-page list of exports being targeted has been published in the commission's Official Journal, but requests to exclude a particular product are now being taken. Any application to have items removed must be accompanied by an explanation as to why alternatives from the EU or outside the US aren't available.

The European Commission, the EU's executive arm, has threatened to impose as much as $4 billion worth of tariffs on US products after a WTO ruling that the tax break was an illegal export subsidy.