Australian Michael Klim and American Jenny Thompson continued to dominate the World Swimming Championships with more gold medal swims on the fifth night in the pool in Perth yesterday.

Klim enraptured his home fans by swimming within a 10th of a second of his world record in taking the world 100 metres butterfly final and with it, his third gold medal of the meet.

Thompson went one better when she landed her fourth gold medal by swimming the third butterfly leg of 100m medley relay for the US women's team, who won in near world record time.

The male swimmer of the championships, 20-year-old Klim led to the turn under world record pace and just failed to lower his record in hitting the wall in a new championship record time for the 100m butterfly of 52.25 seconds. Klim beat home the 1994 world silver medallist Lars Frolander of Sweden (52.79), with fellow Australian Geoff Huegill taking the bronze medal in 52.90 seconds.

"I really wanted this, so I am so delighted," said the shavenheaded Klim, whose three gold medals took Australia's medal haul in the pool to four, second only to the United States, who have 10.

Thompson was part of a brilliant United States team, along with Lea Maurer, Kristy Kowal and Amy Van Dyken, which won by about three metres from Australia in four minutes 01.93 seconds - just 0.26 seconds outside China's world record of 4:01.67 which they set at the 1994 Rome world championships. Australia took silver in 4:05.12, ahead of Japan 4:06.27.

Thompson has already taken gold in Perth in the 100m freestyle, 100m butterfly and as a member of the 100m freestyle relay team. Earlier, China's Yanyan Wu set a championship record in the women's 200 metre individual medley final.

The 20-year-old world record holder from Guangxi won China's third gold medal in the pool when she dominated the final with a time of two minutes 10.88 seconds, eclipsing the event record of 2:11.79 held since 1982 by East German Petra Schneider. It was a Chinese one-two finish, with Chen Yan taking silver in 2:13.66, almost three seconds behind her tearaway teammate. Slovakia's Martina Moravcova took the bronze medal in 2:14.26 - her third medal of the championships.

Kurt Grote captured the USA's ninth gold medal in the programme's opening event yesterday when he withstood Frenchman Jean-Christophe Sarnin to win the men's 200m breaststroke final by .02 of a second.

Another contribution to the story of the championships emerged yesterday when Chinese officials condemned the country's coaches and athletes who use banned substances amid reports that the latest drug scandal could endanger Beijing's chances of hosting an Olympic Games.

Charges of doping against four Chinese swimmers which surfaced at these championships, but related to out-of-competition tests performed before the competition, have dealt a "heavy blow" and "smeared the reputation of Chinese sports" the officials were reported as saying. The publication of the test results on the swimmers followed the discovery of a banned human growth hormone in the luggage of female breaststroker Yuan Yuan as she passed through Sydney Airport en route to Perth, contributing to a particularly bad week for the Chinese.

Sports minister Wu Shaozu blamed the positive tests on rogue coaches and athletes who ignored the country's battle to stamp out drug use.

"The cases during the championships dealt a heavy blow to the Chinese sports," said Wu, who also chairs the Chinese Olympic Committee (COC). "I feel heartbroken about this."

Nick O'Hare clocked 23.94 when finishing sixth and 38th overall in the men's 50 metre freestyle this morning.

Russia's Alexander Popov, the 100m champion, and Australia's Michael Klim set the equal best time of 22.58.