French health authorities have begun investigating whether a procedural failure was to blame for a medical drug trial that sent six men to the hospital, one of whom is now brain dead.
Inspectors from France's health audit and evaluation office, IGAS, were at the laboratory of clinical trial company Biotrial in the north-western city of Rennes on Saturday, broadcaster BFM-TV reported.
Biotrial had been overseeing the now-suspended phase one trial of a drug to treat mood disorders that was developed by Portuguese firm Bial, in which 90 volunteers have taken part.
Six men participating in the trial began to fall ill last Sunday, three days after the trial was launched.
One has been declared brain dead and two are in serious condition, in what France's health minister, Marisol Touraine, has called an unprecedented situation of "exceptional gravity".
Touraine had earlier said that an IGAS inspection would begin Saturday. A technical inspection by the agency responsible for overseeing health products and medication safety, ANSM, has already started.
Investigators are examining whether clinical practice was in line with rules governing drug tests, including at the site of the laboratory and in the volunteer recruitment process.
Biotrial said that its trial was conducted in "full compliance with international regulations," and said it was working closely with the ministry.
The company pays volunteers between 100 and 4500 euros (NZ$169 and NZ$7628) to participate in trials, a common industry practice.