The government has extended a ban on some traditional Chinese remedies in case they contain a toxic herb.

Following advice from the Medicines Control Agency (MCA), any medicines which contain certain species of clematis, akebia, cocculus and stephania cannot be imported, sold or supplied.

The scare was triggered by the discovery that some remedies contained the plant aristolochia, which has been associated with kidney failure.

It can be used as the ingredient "Mu Tong" in medicines - as can the other plant species.

Banning a wider range of species is intended to remove any risk of the toxic plant being mistakenly added to preparations.

There have been two cases of kidney damage in the UK linked to aristolochia - and in Belgium, there were 70 cases after it was used in a slimming preparation.

Aristolochia has traditionally been used in remedies for fluid retention, eczema, and rheumatic symptoms.

The MCA investigation found that, of 63 samples of herbal medicines, 44% contained chemicals which could have come from aristolochia.

'Quality controls not reliable'

Commenting on the ban, Health Minister Lord Hunt said: "The sampling exercise provides clear evidence that quality controls in some parts of the traditional Chinese medicines sector are at present not reliable enough."

He said that the restriction could be lifted in future when the industry had imposed reliable test and quality controls.

The MCA is setting up a joint forum with the traditional medicine industry to discuss safety improvements - and is planning to put a rigorous sampling programme in place.

Chinese medicine experts in the UK say that responsible practictioners have already stopped using the herb in any of their preparations.

Doctors have been warned to ask patients experiencing kidney problems whether they have been taking any traditional Chinese medicines.