U.S. President Barack Obama has apologized after saying he'd been practising his bowling skills at the White House but that his low score was "like the Special Olympics or something."

Obama made the gaffe during an appearance Thursday on "The Tonight Show with Jay Leno."

He told Leno he'd been practising at the White House's bowling alley but wasn't happy about his score of 129.

"It was like the Special Olympics or something," Obama quipped, prompting laughter from the audience.

Even before the taped program aired, Obama had already issued an apology.

On Air Force One, Obama called the chairman of the Special Olympics, Tim Shriver, and apologized.

"He expressed his disappointment and he apologized in a way that I think was very moving. He expressed that he did not intend to humiliate this population," Shriver said Friday on ABC's "Good Morning America."

He said the president's apology was "very sincere" and that Obama had extended an invitation to Special Olympics athletes to visit the White House to bowl or play basketball with him.

Still, Shriver said the incident shows that words hurt and words do matter.

"These words that in some respect can be seen as humiliating or a put down to people with special needs do cause pain and they do result in stereotypes, they do result in behaviour that is neglectful and almost oppressive of people with special needs," Shriver said.

The White House said Friday Obama realizes his quip was a "thoughtless joke."

White House press secretary Robert Gibbs said the president believes that the Special Olympics are "a triumph of the human spirit."

Gibbs added that Obama "understands that they deserve a lot better than the thoughtless joke that he made last night."

Aside from the gaffe, communications expert Stan Collender said Obama "hit it out of the ballpark" with his appearance on the show.

"He was relaxed, he seemed to be in charge and he was able to mix it up a bit with the host," Collender told CTV Newsnet on Friday.

He said Obama's appearance made him seem "real" and "outside the Washington bubble."

Meanwhile, one of the top bowlers for the Special Olympics said that he would destroy Obama in a game.

"He bowled a 129. I bowl a 300. I could beat that score easily," Michigan's Kolan McConiughey told The Associated Press in an interview Friday.

Deborah Bright, who heads up Special Olympics Canada, said Obama's joke was "unfortunate" but added that the flap offers up a good learning experience.

"I think it always brings to light the importance of the choice of words that people use in their day-to-day conversation," she said.

Bright added that the controversy is "a great learning opportunity for people in the U.S. and for Canadians so that they really can get a full understanding of the very positive and powerful effect Special Olympics and sport for people with an intellectual disability."

With files from The Associated Press and The Canadian Press