A Nevada jury has ruled in favour of three women who claimed they developed breast cancer after taking Wyeth’s hormone replacement therapies Prempro and Premarin, and has ordered the group to pay $134.5 million in compensation.

The jury, which is yet to decide whether the company should also pay punitive damages, agreed with the plaintiffs that the company had “concealed a material fact about the safety of the products” and had acted with “malice or fraud”, according to media reports.

Wyeth's stock plunged by more than a quarter in 2002 after a major US government-led study found Prempro was associated with an increased risk of breast cancer, coronary heart disease and stroke. The study, which was due to run until 2005, was terminated at an average follow up of 5.2 years after investigators observed a 26% increase in breast cancer, a 41% rise in strokes and a 29% increase in heart attacks.

According to a Securities and Exchange Commission filing by Wyeth in May this year, the firm is now facing over 5,200 actions brought on behalf of approximately 7,900 women in various federal and state courts throughout the USA for claims of breast cancer, stroke, ovarian cancer and heart disease, allegedly resulting from their use of the conjugated oestrogens Prempro or Premarin .

Wyeth shares slipped $0.38 to $45.78 at close of play yesterday.