California's Supreme Court is expected to rule in the next 90 days if sportswear and footwear giant Nike Inc is guilty of a consumer whitewash over working conditions at its foreign factories.

In a high-profile lawsuit, Nike is accused of breaking California's strict advertising laws by falsely claiming in its 1996-97 ad campaign it guarantees a "living wage" to all workers.

The company also said its workers in Southeast Asia make twice the local minimum wage and are protected from corporal punishment, and that it complies with government rules on wages, hours and health and safety conditions.

The case has already been dismissed by a trial court and a state appeals court, but on Wednesday justices heard arguments whether Nike's defence is "political speech" protected by the first amendment or commercial speech subject to a California consumer protection law.

Nike#;s claims in the ad campaign have been refuted by studies by labour and human rights groups as well as an audit by the firm of Ernst & Young, commissioned by Nike, the suit said.

It alleges the audit found workers in a Vietnam shoe factory were exposed to cancer-causing toluene and suffered a high incidence of respiratory problems.

Nike has always totally denied the allegations. The court is expected to rule on the matter within 90 days.