Communications giant Rogers says it is sorry for showing hardcore pornography in place of a news show on CHCH television this week.

"We apologize to our customers for the inappropriate content briefly shown on CHCH," the company said in a statement. "We're working with CHCH to conduct an urgent investigation and have not yet found the root cause."

"We'll take all corrective measures necessary with CHCH to make sure this doesn't happen again with their feed."

The switch happened on Wednesday afternoon, when CHCH's News Now PM afternoon show was flipped with five seconds of pornography. Only customers who use Rogers as their carrier would have seen the adult footage.

Fanshawe College student Gabe Burchert saw the sex in question at the school's newsroom.

"I looked up and there it is," he said from the school in London, Ont. "I have to admit it was pretty funny."

CHCH also tweeted an apology to its viewers Wednesday evening.

"We have learned that a decoder was reset at one of the cable companies and the first channel it picked up was an adult channel," the statement reads. "We assure you this was an isolated incident which affected a small group of viewers, and did not occur at CHCH Master Control."

"We apologize for the inappropriate content, and will continue to work with our cable partners to ensure this does not happen again."

But this is not the first time CHCH viewers have unexpectedly seen graphic sex.

The broadcaster issued an apology in 2012 after its morning News Now show briefly switched to a sex scene, too.

The station blamed the mix-up on a switching error at one of the cable companies that carries its signal.

CHCH's website says it is available in over 92 per cent of Ontario households and is viewed by millions nationally each week.

adam.carter@cbc.ca