Television entrepreneur Simon Cowell says he's learned one lesson from the US launch of his TV show The X Factor. To keep his big mouth shut.

That means he is not commenting on speculation that music stars such as Britney Spears, Janet Jackson and Black Eyed Peas singer Fergie might become judges when the revamped TV singing show returns to Fox television in September.

Nor is Cowell falling into his own trap again and forecasting the size of the TV audience for the second season, except to say it will be bigger than last year's 13 million average viewers, which was far below his pre-season boasts.

"I shot my big mouth off as usual," the acid-tongued Briton told reporters in a conference call on Wednesday, referring to his forecast that X Factor would draw 20 million viewers, and topple American Idol as the most-watched show on US TV.

It didn't come close, and last month Cowell fired judges Paula Abdul, Nicole Scherzinger and host Steve Jones in a major shake-up.

"I learned a lot from last year... and I think we have learned how we can make the show better," he said.

Cowell said he could not comment on any of the names that have surfaced in recent weeks as possible new judges.

Reuters