A British government ban on tobacco advertising that went into effect last month is beginning to have a negative effect on race sponsorship in the country.Doncaster Racecourse and Rothmans Ltd. announced Tuesday that as a result of the The Tobacco Advertising and Promotion Act, which came into effect February 14, 2003, Rothmans will no longer sponsor the St. Leger Stakes -- the world's oldest Classic which had a 2002 purse of £400,000. Rothmans is also pulling its sponsorship of three other prestigious races at the St. Leger Festival -- the Park Hill Stakes, May Hill Stakes and the Champagne Stakes -- as a result of the advertising restrictions.Rothmans had sponsored the St. Leger Festival for the past four years, with two years remaining on its commitment."We will always be grateful to Rothmans and their highly professional team for the enormous benefits they brought to the St. Leger Festival in the way of marketing and promotional expertise as well as through their generous financial support," said John Sanderson, chief executive at Doncaster Racecourse commented. "They leave Doncaster Racecourse with an enhanced St. Leger Festival and four top class and well developed opportunities for new sponsors."Ralf Wittenberg, marketing director of Rothmans added, "Rothmans Royals has enjoyed a long and prosperous relationship with top class Flat racing and in particular with the St. Leger Festival at Doncaster Racecourse. Although saddened to be losing this wonderful sponsorship opportunity, we are delighted to have contributed to the re-establishment of the St. Leger as one of the North's premier sporting occasions. We wish Doncaster racecourse well and feel confident that another equally enthusiastic sponsor can be found for this world class sporting event."