American football fans see porn during Superbowl broadcast in Ari

CLIPS from a porn movie were shown to American football fans as they watched the closing minutes of the Superbowl.

The Comcast cable company has described the incident as "an isolated malicious act", the Arizona Daily Star reports.

Part of a movie being aired on an adult channel was broadcast to viewers in Tuscan, Arizona, with less than three minutes left on the clock.

The incident happened just after the Arizona Cardinals scored a touchdown to put the team in the lead.

It is not known how many Superbowl fans were affected by the interruption – which featured full male nudity – but Comcast said viewers with high-definition televisions would not have seen the clip.

Those that witnessed the mistake told the Star they saw a woman unzipping a man’s pants before the pair engaged in a graphic act.

Some said they thought it was an advertisement at first.

"I just figured it was another commercial. ... then he did his little dance with everything hanging out," viewer Cora King said.

Comcast spokeswoman Kelle Maslyn said the clip was not a result of a technical problem.

"We did an extensive preliminary check on our technical systems, and everything appeared to be working properly when the incident occurred," Ms Maslyn said.

The US Attorney’s office said it was looking into the incident.