The Vancouver Sun reported that Armstrong, a retired dentist, was arrested in Blaine, Washington State, on April 15.

The arrest came after Federal Food and Drug Agency (FDA) and Postal Inspection officials alleged they watched him pick up a box of nearly 3,000 pills mailed from a manufacturer in China.

He was charged with trafficking in counterfeit goods and released after waiving his extradition rights and posting a $20,000 (£13,000) bond.

Armstrong, who took up wheelchair curling after suffering from bad knees and a traffic accident in 2003 left him unable to play in able-bodied competition, faces up to 10 years in jail and a fine of up to $2 million (£1.3 million) if he is found guilty.

The Vancouver Sun reported that FDA Special Agent Jim Burkhardt said authorities were tipped off to the shipment when it arrived at a clearing house in Los Angeles on April 7.

When customs agents opened the box, they found 2,544 tablets of a drug labelled as Viagra, and another 260 tablets labelled Cialis.

Burkhardt said although the pills bore trademarks of the drug makers, Pfizer and Lilly, they were suspected to be counterfeit because they had been shipped from China, which is known for the production of counterfeit drugs.

"Viagra and Cialis are also some of the most common drugs targeted by counterfeiters," he told the Vancouver Sun.

"Many, if not most, counterfeited drugs are made in the People's Republic of China."

Burkhardt said he confirmed with both Pfizer and Lilly that the Chinese pills were fakes and that they were also packaged with fake product lot numbers.

The agents let the package, which was addressed to Armstrong's wife Carleen, continue on its journey to a commercial mailbox company in Blaine, and when Jim Armstrong came and picked it up, they arrested him on the spot.

Burkhardt said a review of the mailbox company's records showed "a very large number of parcels or boxes arriving at this postal mailbox from various foreign countries, including China and India."

Carleen Armstrong died of cancer last September.

Armstrong's next appearance in court is scheduled for April 30.