Taxpayers aren't footing the bill for Kanye West's headlining performance at the Pan Am Games closing ceremony, organizers said Monday.

And the head of the Games organizing committee said even he isn't sure whether the rapper's mic problems and abrupt exit from the stage Sunday night were genuine or planned.

Pan Am Games CEO Saad Rafi said performance fees for West and the two other artists — Canadian howler Serena Ryder and Miami pop-rapper Pitbull — were covered by the concert promotion company Live Nation, which sponsored the Games.

"That was part of the relationship with Live Nation, that we weren't paying performance fees to artists that they would secure," he told The Canadian Press.

"I don't know whether they pay full price or not but it's part of their sponsorship with us and they contract with the artists."

The Games organizing committee only contributed to expenses such as backing bands, makeup artists and transporting artists' equipment from the airport, Rafi said.

There was a fleeting outcry when West was announced as the headliner for the ceremony, with several thousand people signing a petition urging organizers to replace him with a Canadian act.

Some questioned whether tax dollars should be spent on an American and often controversial artist.

The crowd roared its support for West at Sunday's event, but many expressed their confusion when he tossed an apparently faulty microphone up in the air and stomped off stage.

"Did Kanye West just throw the mic in the audience and walk off the stage unceremoniously!?! .PanAmGames .closingceremony," one person wrote on Twitter.

"So Kanye West just throws the mic and leaves. I guess they only paid him till 10pm. .PanAmGames .closingceremony .RogersCentre," another tweeted.

Rafi said West is known to do the unexpected and "we may never know" whether his departure was staged.

"The volume that he performs at is so high, it might have been what affected the sound system, but it also might be something his team planned all along, so you just never know because he's such a creative guy," Rafi said.

"His team controls his whole part of that show — lights, etc.," he said, adding that he hadn't heard any complaints from West's camp since the show.

Nearly 40,000 spectators packed Toronto's Rogers Centre for the closing ceremony, about 5,000 fewer than for the sold-out opening ceremony on July 10.