Five out of the six problematic products were manufactured on the mainland and were labelled huichunsu, meaning 'back to youth'. Mercury overdoses may damage the nervous system and kidneys.

According to the mainland's hygiene standard for cosmetics, the safety limit for mercury is 1 part per million.

One of the samples, a seven-day package of Xinjiaoli Huichunsu, was found to contain 12,000 to 15,000 ppm of mercury.

Another two 10-day whitening packages of the same brand contained mercury levels of 1.6 times to 13,000 times the limit.

Three other products, Youmei Huichunsu, Jiaoli Huichunsu and Mui Lee Hiang - Cream for Acne and Blemishes, exceeded the mainland standard by 3,700 to 6,700 times.

Apart from the 19 low-cost face creams, 30 samples of creams from the higher-end market, priced between HK$158 and HK$2,100, were also tested. All 30 samples were satisfactory.

Council chief executive Connie Lau Yin-hing said it received 126 complaints about face creams in the first seven months of the year for allergies, 'unsatisfactory effects' and being past their use-by date.

Ms Lau recommended that shoppers test samples of face products on their hands overnight before purchasing them.

Former Medical Association president Choi Kin said symptoms of mercury poisoning included trembling hands and a change in personality. A black line or dots might also appear on the gums.

The symptoms would surface after users applied creams containing mercury for one or two years.

In serious cases, the limbs of poisoned users could become rigid 'like Parkinson's patients', he said.

The Customs and Excise Department seized 242 problematic face creams in the past seven months, a spokesman said.