China's swimmers have been told they will have to pass a blood test before they can compete in this year's Olympic Games.

The country's sporting authorities are aiming to avoid a repeat of the drugs scandals that have affected Chinese swimming over the past decade.

In 1994 the team won 23 Asian Games swimming golds, but had to hand back nine of them after positive tests,

At the last world championships two years ago, four swimmers failed dope tests, while another team member was found in possession of a large amount of Human Growth Hormone.

"We're working hard to crack down on doping," insisted Zhang Qiuping, vice chairman of the China Swimming Association.

"Last year we started blood-testing our swimmers, which is more thorough than testing urine samples."

Zhiang said 700 urine checks, and 100 blood tests had taken place in 1999 in an initiative supported by the sport's world governing body Fina.

"We're encouraged by the work China has done in driving out drug use," said Fina honorary secretary Gunnar Werner.

Up to 10 Chinese swimmers and swimming coaches were suspended for doping offences in 1999.

Chinese state media reported in June last year that top Chinese swimmer Xiong Guoming faced a life ban testing positive for the second time.

"We had a few black sheep and that has had a negative impact on us, but we're tackling the problem by stricter drug tests and harsh punishment," Zhang said.

The sports of cycling and triathlon have already agreed to blood testing at next year's Olympics, with cycling having enforced them since 1997 - despite a negative image for that sport

In athletics, competitiors such as Britain's long distance runner Paula Ratcliffe have called for a similar policy.

But like track and field, blood testing is still voluntary in swimming, despite high profile advocates such as former multiple Olympic champion Mark Spitz of the US.

The practise is more effective than urine-testing in detecting human growth hormones and erythropoietin (EPO).

But critics say blood testing is inconvenient and could affect the performance of swimmers if carried out before competition.

China have not been dominant in recent events, but Zhang said this was not down to an anti-doping policy.

"We're not so hopeful in the coming Games because our younger swimmers, which will replace the older ones, haven't had enough international exposure," he said.

"There's a vaccuum in between."