Tactical Response Group police wearing bullet-proof jackets were providing roundthe-clock protection at a Perth hotel for a Chinese swimming team in disgrace following Australian Customs' chance seizure of what is suspected to be banned human growth hormone at Sydney Airport yesterday.

Customs seized 13 vials suspected of containing the growth hormone Somatotrophin in a bag belonging to the 21-year-old breast-stroker Yuan Yuan as she passed through customs with the Chinese team en route to the world championships in Perth.

Yuan, who won silver (200 metres) and bronze (100 metres) at the 1994 world championships in Rome, is the lowest-ranked Chinese swimmer at these championships with a 1997 world-ranking of 13.

Yesterday's 29-member Chinese contingent arrived in Sydney shortly after 10.50 a.m. after flying from Beijing. They had a stopover in Melbourne, though none of the party left the plane. The entire delegation was questioned then flew to Perth on their scheduled flight to link up with the 12 Chinese swimmers who have been training in Perth since Tuesday.

The clear vials, each about 2.5 centimetres long and labelled in English with Somatropin and Norditropin (the brand name of Somatotrophin), were discovered after a customs officer decided to search a person travelling with the team who "matched the profile of a narcotics suspect".

The suspect, who was sharing a baggage trolley with Yuan, was found to be carrying nothing of concern, but on searching Yuan's gear, customs found the drugs packed in ice inside a battered thermos flask in a plastic bag. Thirteen vials of saline solution (saline is used to dilute drugs that are to be injected) were also found. The Chinese team had not declared the substance, which is a banned import.

An English-speaking coach immediately claimed ownership of the vials. He claimed he did not have time to pack "the medicine" for a colleague in his own bag. However, on checking all paperwork, no one was found to have documentation to show they needed the drug as a legal treatment. Later, a Chinese journalist said at Perth airport that the team claimed the substance was turtle jelly.

The maximum penalty for carrying a prohibited substance is Aus$50,000, but customs said that, in this case, it was more likely to be a warning because of the small quantity found.

In Perth, the remaining members of the team were told yesterday morning of the seizure by officials from the Australian Sports Drug Agency, who arrived at the suburban pool where they were training to escort all 12 swimmers for drug-testing. The nine-times Olympic champion Mark Spitz said he believed the Chinese may have had an ulterior motive should the analysis today prove the substances are banned drugs.

"I would say they have brought these drugs in here to see if they pass the test with some of their lesser swimmers, if in fact they do get tested," the American said. "And if those drugs happen to actually slip through the cracks, then they are going to implement those drugs obviously in the future. This is a longterm objective, I think."

Olympic officials admit they, as yet, have no way of testing for one of their five banned substances, peptide hormones - which include human growth hormones. These drugs were highlighted by China's critics as the most likely reason the country's women, after winning only one swimming gold medal at the 1996 Olympics, set 10 times that were better than Atlanta's best at their National Games in Shanghai last October. Seven members tested positive for the anabolic steroid DHT (dehydrotesterone) before the 1994 Asian Games in Hiroshima in September, two months after their women swimmers won 12 of the 16 events at the world championships in Rome, and since 1990, Chinese swimmers have returned 23 positive tests to banned substances.

For China, their world championships are already over, whatever happens in the pool over the next fortnight. "Every competitor in the pool will be looking at them and saying: `You're doped'," the World Swimming Coaches Association executive director John Leonard said. And this time, the Chinese cannot argue.