Beijing - South African Olympian Natalie du Toit grabbed her third gold of the Paralympics on Thursday on a day tarnished by more doping scandals and a ruling that an athlete is not disabled enough to compete.
As China pulled clear at the top of the medals table, Du Toit smashed her own world record in the women's 200m individual medley, leaving her competitors trailing as she bids for a five-gold clean sweep.
But away from the action, two powerlifters were slapped with two-year bans after traces of steroids were found in their bodies, organisers said.
Facourou Sissoko, 46, a male competitor from Mali, and Ukranian female powerlifter Liudmyla Osmanova, 22, both failed pre-competition tests, the International Paralympic Committee said.
The positive results bring the number of powerlifters expelled to three. Pakistani Naveed Ahmed Butt, 37, tested positive for a steroid on September 4, it was announced on Tuesday.
On Wednesday, German wheelchair basketball player Ahmet Coskun was kicked out of the Paralympics for taking a banned drug that can conceal performance-enhancing substances, although he insisted he took it only as a hair loss treatment.
A total of 461 tests had been carried out, both in and out of competition, by the end of Tuesday.
Meanwhile, Irishman Derek Malone was banned from the Games because authorities deemed him not disabled enough, Irish sports chiefs said Thursday.
The Paralympic Council of Ireland (PCI) was notified this week that Malone, 28, who suffers from cerebral palsy, was ineligible to take part in the seven-a-side football tournament in Beijing.
Cerebral palsy is an impairment resulting from injury to the developing brain that leads to altered neuromuscular function, but the condition can improve with athletic training, as was the case with Malone.
"I'm bitterly disappointed and frustrated by the whole process," Malone, who won a bronze medal in his class in the 800m track in Athens in 2004, told reporters Thursday.
PCI secretary general Liam Harbison said Malone had been punished for training hard and pursuing excellence.
The ruling comes after Australian athlete Jessica Gallagher was last week told she was not blind enough to compete.
The controversies have taken some of the gloss of what has otherwise been a celebration of disabled sports, led by the performances of Du Toit, fellow South African "Blade Runner" Oscar Pistorius and the dominant Chinese.
Du Toit did her best to force the focus back on the pool on Thursday evening, swimming 2 min 27.83sec, and finishing almost 10 seconds clear of Canada's Stephanie Dixon.
The 24-year-old has already taken gold in the 100m butterfly and 100m freestyle events in her class.
"I just went out there and had a good race. I just enjoyed it. I felt good in the warm-up so to get out there and have a good race was a bonus," she said.
Du Toit, who finished 16th in the 10km marathon swim in the Olympics last month, is aiming for two more wins to match her gold tally at the 2004 Athens Paralympics.
She is one of only two Paralympians who also competed at the Beijing Olympics, along with Polish teenager Natalia Partyka, who won table tennis gold in her class on Wednesday
Du Toit won five golds and a silver in Athens. She lost her left leg in a road accident in 2001, after narrowly missing qualification for the Sydney Olympics a year earlier.
China stood on 33 golds late Wednesday evening, six clear of Britain. But the home nation had 96 medals in total, to Britain's 57. South Africa has 12 medals, eight gold, one silver and three bronze
More than 4 000 competitors from nearly 150 countries and regions are battling for 472 gold medals in 20 sports at the eye-catching venues used for the Olympics such as the "Bird's Nest" and the Water Cube.