One person was reported brain dead and five others critically ill in north-west France after taking part in a drug trial. The French health ministry said in a statement on Friday that the six persons were taking part in a clinical drug trial for an unnamed pharmaceutical company. The ministry also did not disclose what the drug was meant for. A person familiar with the case said they were testing a cannabis-based painkiller, Reuters reported. Local media reported that the trial took place at the Biotrial clinic.

The brain-dead volunteer was admitted to a hospital in Rennes on Monday, while the others were hospitalised on Wednesday and Thursday. The trials have been suspended, and all volunteers who took part in them are being called back. The ministry said the six volunteers were in good health until they took the oral medication manufactured by a European laboratory. “This test was carried out at a private facility specialized in carrying out clinical trials,” it said.