Kris Allen beat Adam Lambert to win the singing competition
American Idol bosses have rejected allegations of vote fixing after fans were shown how to "power-text" for this year's surprise winner, Kris Allen.
Show sponsor AT&T sent employees to two Allen supporter parties in Arkansas where they provided phones capable of sending 10 text message votes a time.
But TV network Fox dismissed the claim, saying: "In no way did any individuals unfairly influence the outcome."
It added voting procedures were closely monitored by independent adjudicators.
"Fox and the producers of American Idol are absolutely certain that the results of this competition are fair, accurate and verified," a statement said.
"Kris Allen is, without a doubt, the American Idol. We have an independent third-party monitoring procedure in place to ensure the integrity of the voting process."
The Arkansas Democrat-Gazette reported that AT&T staff brought more than 80 mobile phones to Allen parties during the final performance night last week.
One fan said she voted for Allen 10,840 times on one of the free phones provided, despite American Idol rules forbid "power-voting" using "technical enhancements".
AT&T's mobile phone network is the only one on which Idol watchers can cast votes through text messages, and voting usually incurs a charge.
While AT&T bosses admit their staff did show fans how to vote for Allen, they maintain the extra votes did not hamper other finalist Adam Lambert's chances of success.
"Going forward, we will make sure our employees understand our sponsorship celebrates the competition, not individual contestants," the company said.
"That said, it's quite a leap to suggest that a few individuals could have impacted the final results."
American Idol viewers are able to phone-vote to the programme free of charge.