The claims have surfaced after a Bhutanese princess allegedly smuggled 22 rhino horns and nine bear galls with a street value of up to US$1 million (HK$7.73 million) into Taiwan after buying them in Hong Kong.

It was only because Bhutan and Taiwan do not have diplomatic relations - and because the Taiwanese Foreign Ministry maintained the case should be handled according to ordinary criminal proceedings - that the alleged royal smuggling case came to light.

Hong Kong was recently pinpointed by the United Nations as a hub of the grisly trade in rhino horn, and airport and Government officials promised to step up their efforts to stop smuggling.

Ms Patel claimed the case under investigation in Hong Kong and awaiting trial in Taipei could be an example of the problem.

''There is a lot going through customs under diplomatic immunity and therefore not being discovered,'' she said. ''It has been well documented and there is lots of evidence.'' Kai Tak Airport Command admitted the use of diplomatic couriers to transport contraband was ''a possibility'', and launched an investigation after animal rights groups and the Taiwanese Government criticised Hong Kong for failing to detect the alleged royal smuggling case.

Acting head of Airport Command Anna Poon Shiu Yuk-han admitted people were concerned endangered animal parts had been smuggled through the territory.

''We are investigating, partly on behalf of other agencies like the Agriculture and Fisheries Department,'' she said.

''We believe the alleged smuggler spent three days in Bangkok before flying to Hong Kong for two weeks. I am trying to confirm which flights were taken and which countries were visited.'' She said Hong Kong customs officers had never caught any diplomatic passport-holders attempting to smuggle anything, but Customs officers were not allowed to search their bags unless they received a tip-off and got special permission to do so, usually infront of consular representatives.

The airport investigation comes weeks after customs officers and officials from Hong Kong's Agriculture and Fisheries Department vowed to step up efforts in intercepting illegal consignments.

This followed reports that Hong Kong was a major transit point for the outlawed trade in rhino horn made by the EIA and the World Society for the Protection of Animals, which made the allegations to the United Nations Convention on International Trade inEndangered Species (CITES).

Police in Taiwan say Princess Deikiy Wangchuck told them she bought the animal parts in Hong Kong and planned to sell them in Taiwan as she had heard they fetched enormous prices.

Taiwan has been harshly criticised for condoning the trade, but is cracking down to avoid the imposition of economic sanctions by the US.

The Taiwanese Government recently raised the penalty for rhino horn smuggling, and Wangchuck could face up to two years in jail and a fine.

The seizure allows Taiwan to produce a good report card to CITES officials, who are expected to visit in November to check the country's wildlife protection efforts.

CITES postponed making a decision on whether to impose economic sanctions on Taiwan because of the island's rhino horn trade, but United States President Bill Clinton has warned them to improve their efforts.

Wangchuck, a graduate of Cambridge in Britain, was arrested and charged with smuggling products from endangered species and violating conservation laws. She is on bail awaiting trial.

The divorced princess has children and runs an import business in Bhutan. Her government has not made any official statements about the case, and has not requested diplomatic immunity.

The kingdom of Bhutan is committed officially to wildlife preservation, with any trade in animal parts or products carrying a heavy penalty.