'At this stage, we are not sure if they really contain cannabis or tetrahydro-cannabinol. THC is a type of psychotropical substance and could affect nerves. It is a controlled drug in Hong Kong,' a division spokesman said.

Chan Man-fai, Government Laboratory senior chemist, said results should be available this week.

He said it was illegal to keep or sell cannabis or products containing THC - a derivative of marijuana.

Body Shop spokeswoman Curi Yiu Kar-lei admitted it was aware the products contained the substance.

The shop launched products containing hemp seeds last week, including lip salve, soap and hand cream.

'We use hemp seeds because the oil extracted from these is known as highly moisturising and good for skin care,' she said.

Body Shop had launched the products in Britain, other European countries and the United States and the products were legal, Ms Yiu said. Police in France had seized the products in August but officers later admitted it was a misunderstanding, she said.

'We, of course, are not promoting drugs. The THC contained in our products is very, very low - every 1,000 grams will have less than three milligrams of THC,' she said.

'We are using industrial-use hemp seeds, which are different from marijuana. Hemp seeds are usually used to make jeans and ropes.' Ms Yiu said the company was awaiting results from the laboratory.

Associate Professor Lee Kwing-chin from the Chinese University's department of pharmacy said there were various types of THC and some were used in medical treatment to prevent vomiting.

He said he could not rule out the possibility that drugs put on the lips could enter the bloodstream and have an effect on the user.