One of the world's largest cigarette companies, Britain's Imperial Tobacco, has been drawn into a row over the sponsorship of a major televised European tennis event.

Health organisations are furious that the main sponsor of the Basle ATP World Tour 500 tournament in Switzerland is Davidoff, the luxury brand that covers everything from cigarettes to cigars and aftershave. Davidoff's cigarette brand is owned by Imperial.

The EU banned all tobacco advertising in its member states in 2005. But Switzerland is not in the EU and tobacco sponsorship is legal. Satellite broadcaster Eurosport has dropped plans to carry the event after French anti-tobacco campaigners threatened legal action if the tournament was screened in France. Instead, the event will now be carried by a German satellite broadcaster.

The tournament's close association with tobacco has prompted fury from the World Health Organisation and European campaign groups, including the UK's Action on Smoking and Health (Ash). More than 500 eminent health experts have signed an open letter calling on Roger Federer, the Swiss world number one player, to pull out of the tournament. Federer has declined to respond.

Unesco, the UN's cultural arm, which received a donation from the event's organisers, has returned the money and demanded it no longer be associated with the tournament. A spokesman for Imperial declined to comment.