(Reuters) -British travel retailer WH Smith lowered its annual profit outlook on Thursday after a review revealed earnings had been overstated in its North America division, sending its shares tumbling over 30%.

WH Smith said it lowered its fiscal-year guidance for its North America division after the identification of an overstatement of around 30 million pounds ($40.4 million). The British retailer on Thursday said that it now expects headline trading profit--one of the company's preferred metrics--for the division for the fiscal year ending Aug.