LOS ANGELES (AFP) - Al Jazeera insisted on Tuesday (Dec 29) that it had never alleged Denver Broncos quarterback Peyton Manning used human growth hormone (HGH), the most explosive insinuation in the network's major investigation into doping in sports.

Al Jazeera reporter Deborah Davies attempted to clarify the report in a follow-up on NBC's Today show, saying saying that the documentary had not stated that Manning had used the banned substance.

"We have not said that in the programme," she said.

She said the report had merely cited a former employee of the Guyer Institute in Indianapolis, Mr Charlie Sly, who claimed to have knowledge that HGH was shipped to Manning's wife Ashley.

"The only allegation in the programme from Charlie Sly is that growth hormone was sent repeatedly from the Guyer to Ashley Manning in Florida," she said. "We're not making the allegation against Peyton Manning."

Manning has threatened to sue over the report.

"Let's make it clear what the allegation is. The allegation in the programme is very simple, that when Charlie Sly worked in the Guyer doing part of his training ... the clinic was sending out not one shipment but repeated shipments of growth hormone to Ashley Manning in Florida. That's it," Ms Davies said.

Most media following up on Al Jazeera's report have seen a clear implication made in the documentary, The Dark Side, that Peyton Manning was the eventual recipient of the drug shipments.

In report, Mr Sly said: "All the time, we would be sending Ashley Manning drugs. Like growth hormone, all the time, everywhere, Florida. And it would never be under Peyton's name, it would always be under her name."

Mr Sly has since recanted everything he said in the documentary and alleged that some of his calls and conversations were recorded without his consent.