Oprah Winfrey with Stevie Wonder, John Travolta and Tina Turner

Singers Stevie Wonder and Tina Turner played a musical tribute to the TV presenter on a special edition of her long-running talk show.

Actor John Travolta acted as master of ceremonies on the show, which will be seen by millions around the world.

Oscar winners Nicole Kidman, Halle Berry and Sidney Poitier also made appearances during the celebrations.

Poitier spoke about Winfrey, who was raised in a poor family in the American South and went on to earn a personal fortune estimated in excess of �1bn (�552m).

"Wherever they are spending themselves in trying to hold back the darkness as hope flickers weakly, you are there in remembrance of the light inside themselves," he said.

Long-running show

Winfrey's show, which is screened five times a week in the US, is in its 18th season.

The programme is already scheduled for the 2007-8 season.

It has also become famous for its book club and has managed to outlast a whole host of rival talk shows on American television.

Like her 50th birthday party show, Winfrey has also attracted a series of star guests to come and talk on her programme.

As well as a public celebration, Winfrey is set to mark the occasion with 50 close friends at her California ranch this weekend.