The International Cycling Union said the seven-time Tour de France champion can compete in the Jan. 20-25 Tour Down Under, his first race since coming out of retirement after three years.

A strict application of dope testing rules would not have allowed the 37-year-old American to compete until February 1, 2009, six months after he filed paperwork with the US Anti-Doping Agency.

But the UCI said on Wednesday that Armstrong could return early because its drug-testing standards have improved since the rule was drawn up four years ago.

"Riders are now subject to a much-reinforced system of monitoring compared to that of the past," the governing body said in a statement.

"Lance Armstrong has and will be the subject of very strict monitoring throughout the period running up to his return to the peloton."

Armstrong's comeback is meant to draw attention to his global campaign to fight cancer, a disease he survived before winning seven straight Tours from 1999-2005.

It is also a defiant stand against critics who doubt he could have achieved those victories without the use of performance-enhancing drugs.

Now he is liable to be tested at any time without notice and will have his own biological passport as part of a UCI-backed scheme to monitor possible doping offenses.

Riders must give a series of blood and urine samples which allow a World Anti-Doping Agency-accredited laboratory to measure abnormal fluctuations in body readings.

Armstrong said last month he was tested in late August, and has enlisted a personal anti-doping expert in Don Catlin, who will make his test results available to the public.

Catlin, who ran the first anti-doping lab in the United States at UCLA for 25 years, will freeze and keep samples of Armstrong's blood to be analyzed in the future.

Armstrong will not be paid for returning to the saddle and the testing costs will be covered by his Kazakhstan-based team Astana, which is managed by his cycling mentor Johan Bruyneel.

His comeback race, the Tour Down Under, is the first event on the UCI ProTour calendar in 2009 and is likely to be followed by the Tour of California in February.

"It was a great decision based on the up-to-date information in respect of profiling that is required for riders," Tour Down Under director Mike Turtur, a former Olympic cyclist, said today from Adelaide.

"I think the UCI has made a wise decision for the promotion of the sport in the Oceania region." The political leader of South Australia state also welcomed the news.

"This is fantastic news for South Australia, cycling and the general community who will benefit greatly from Lance's cancer awareness campaign," Premier Mike Rann said.

"His participation will double the number of visitors and is expected to quadruple the worldwide television coverage."