French health and security authorities on Tuesday warned against honey and gel products being marketed as natural aphrodisiacs but which in fact contain ingredients not marked on labels that may have dangerous side effects.

Anyone who has bought the "should above all not consume them but destroy them", French anti-fraud, customs and health products safety agencies said in a joint statement.

They said the products, marketed under names like Black Horse Honey and Jaguar Power, claim to be natural but actually contain chemical products like sildenafil or tadalafil.

These are the main substances in the anti-erectile dysfunction drugs Viagra and Cialis, which in France are only available on prescription.

These substances can have serious side-effects in people suffering heart conditions, the agencies warned, saying clinics had in the last months reported several cases of people who had consumed the products.

These included "repeated convulsions, pulmonary hemorrhages, brain swelling, or major acute renal failure that, for some, resulted in hospitalisations," the agencies warned.