The Dutch food and consumer watchdog issued a warning Thursday about a batch of herbal tea imported from Bulgaria which may have been contaminated by a highly toxic nightshade plant.

The tea, supplied by Dutch herbal tea supplier Jacob Hooy, "has probably been contaminated by deadly nightshade, a plant that's dangerous to peoples' health," the NVWA said in a statement.

Three types of herbal tea called "marshmallow root", "bile cleansing herb" and "airways herb", sold at outlets in Amsterdam, Utrecht and Rotterdam have been taken off the shelves.

"Shops have taken these teas off the shelves and people are advised not to drink it," the NVWA said.

It added it was unknown how deadly nightshade, which if ingested causes confusion, and death, ended up in the , which was imported from Bulgaria through a German supplier.