AceShowbiz - Whitney Houston's aides are rushing to dismiss reports the R&B superstar has returned to her drug-taking ways after the singer pulled out of a string of European dates. The star has been diagnosed with a severe respiratory infection and she is now seeking medical attention in a French hospital.

But U.S. magazine In Touch suggests Houston's latest illness could be drug-related following an eye-witness account of her behavior at a Los Angeles hotel in March. Marlon David was sitting on the table next to Houston and her ex-husband Bobby Brown during a night out at the Beverly Wilshire hotel on March 10 and tells In Touch, "I saw her pull a plastic bag out, put a folded bill to her nose and discreetly snort a line from it of what to me certainly looked like cocaine. She's extremely thin and looks like a disaster."

But Houston's representatives have blasted the report, insisting the singer is not using drugs. David also tells In Touch the night out ended badly for the former couple, following a heated argument. He adds, "He (Brown) had so much trouble trying to control her. He tried to make her leave, but she wouldn't. She started yelling his name loudly and calling him a stupid son of a b**ch, and he told her to shut the f**k up."

Meanwhile, reports in the French press suggest the singer was admitted to a Parisian hospital, while a representative for the star confirms Houston was treated by medics for chronic rhino pharyngitis, a swelling of the membranes in the nose and throat.