It is one of Europe's busiest waterways, a formidable conduit that handles millions of tonnes of traffic a year. But yesterday it emerged that the Rhine contained a lot of something else - cocaine.

　　According to researchers at the institute of biomedicine and pharmaceutical research in Nuremburg, almost 11 tonnes of the drug, worth some ?1.64bn, was flushed into the river last year, the equivalent of 30kg (66lbs) of cocaine a day.

　　Some 400,000 Germans take the drug at least once a year, they believe, higher than previous government estimates.

　　"If the institute's results are correct, then the actual numbers for cocaine consumption are much higher than the accepted figures," Roman Simon, of the Munich research institute, which delivers data on drug use to the German government and the EU, told Der Spiegel magazine. The same researchers provoked outrage five years ago after discovering traces of cocaine in the toilets of the Reichstag parliamentary building in Berlin.

　　The findings appear to mirror a recent study in Britain, which claimed that 2kg of the drug end up in the river Thames every day.