French health minister Marisol Touraine has said one person is brain-dead and five others are in a critical condition after the clinical trial of a new drug went wrong, AFP has reported.
The trial, of an oral medication, was taking place at a clinic in Rennes, in Brittany.
There had been reports that the drug being trialled contained extracts of cannabis, but the health minister denied this.
Touraine added the trial had been suspended and the other volunteers had been recalled.
She said she will visit Rennes today.