Athletes may have to wear oxygen masks at the Commonwealth Games in Kuala Lumpur in September because of the high levels of smog in the Malaysian capital.

New Zealand team doctor Richard Edmond is ready to take the drastic step for the Kiwi athletes who succumb to the polluted air. "I think we'll have to take lots of oxygen with us and try to get to them as soon as possible," Edmond said.

"I don't like the thought of athletes having to wear masks. I think if it got that bad, then they just couldn't possibly compete."

Edmond, a team doctor at three Olympic Games and two Commonwealth Games, will head a 12member medical team - the Kiwis' biggest ever for a Games because of the pollution problems.

"It's a medical concern," Edmond said. "I've read that breathing the smog there at the moment is the equivalent of smoking 1,000 cigarettes a month, so you can imagine what that does to lungs.

"People who aren't used to that certainly will be affected with their breathing."

Edmond will travel to Kuala Lumpur in late July to ascertain the level of smog, and the heat and humidity, which he believes will pose further problems for athletes.

The International Olympic Committee (IOC) further strengthened doping rules yesterday by upgrading diuretics to masking agents and adding insulin to its banned list.

IOC medical commission chairman Prince Alexandre de Merode said diuretics, or weight loss drugs, could be used to mask other banned substances like steroids or a high testosterone level.

Insulin, used by diabetics to help counteract their illness, can be used by athletes to boost muscle mass. But De Merode said diabetics would still be allowed to compete and use insulin.