US sports fans in Arizona got a surprise when their TV coverage of American football's Super Bowl was interrupted by a pornographic film.

Tucson-based KVOA-TV said it was "dismayed and disappointed" after some cable viewers had their match coverage disrupted towards the end of the game.

The company said the material was only seen by viewers of one cable network.

"KVOA will investigate what happened and make sure our viewers get answers," company president Gary Nielsen said.

"When the NBC feed of the Super Bowl was transmitted from KVOA to local cable providers and through over-the-air antennas, there was no pornographic material," he added.

Comcast, the cable company whose viewers saw the material, said it was investigating.

Local media outlets reported that they received calls from furious viewers.

The clip showed a woman unzipping a man's trousers, followed by a graphic act between the two.

"I just figured it was another commercial until I looked up," viewer Cora King told the Arizona Daily Star.

"Then he did his little dance with everything hanging out."

The interruption happened just after the last touchdown by the Arizona Cardinals, who lost the match to the Pittsburgh Steelers.