Oprah Winfrey has dismissed reports Mariah Carey has cancelled an appearance on her U.S. chat show on Friday, when she was allegedly set to announce she is pregnant.

The singer was rumoured to have booked an appearance on the show to share the news that she is expecting her first child with husband Nick Cannon, according to internet reports.

But a representative from Winfrey's production company, Harpo, insists there are no scheduled plans to have Carey on the show either now or in the immediate future.

Meanwhile, Carey's spokesperson has shot down claims the star is pregnant - a rumour she that has plagued her since exchanging vows with Cannon in April after a whirlwind romance.