LOS ANGELES • Five-time National Football League (NFL) Most Valuable Player Peyton Manning has branded allegations in an Al-Jazeera documentary that an Indianapolis anti-ageing clinic supplied him with human growth hormone (HGH) as "complete garbage".

"The allegation that I would do something like that is complete garbage and totally made up," the NFL star said in a statement issued through the Denver Broncos to the US media. "It never happened. Never. I really can't believe somebody would put something like this on the air. Whoever said this is making stuff up."

Neither the NFL nor the Broncos commented on the allegations, which were included in an Al-Jazeera investigative report due to air last night, but which was shared in advance with US website The Huffington Post.

According to the website, in the report titled The Dark Side, British hurdler Liam Collins went undercover to expose the use of performance-enhancing drugs in sports.

As part of his probe, he met Charles Sly, a former pharmacist at the anti-ageing Guyer Clinic in Indianapolis, where Manning once played for the NFL's Colts.

Sly said he mailed HGH to Manning's household in 2011, sending it to Manning's wife, Ashley, to avoid a link to the sports star.

However, in a follow-up interview with Al-Jazeera, Sly recanted the allegation, saying it was "absolutely false and incorrect".

The NFL collective bargaining agreement ratified in 2011 banned the use of HGH. However, the league did not begin testing for the substance until last year.

Manning missed the 2011 season because of multiple neck surgeries, and joined the Broncos as a free agent before the 2012 campaign.

The clean-cut 39-year-old is one of the icons of the NFL and the most marketable player of his generation, earning around US$12 million (S$ 16.8 million) a year from endorsements, according to Forbes.

AGENCE FRANCE-PRESSE