Secret's out: Leona Lewis flashes her 'engagement' ring

Although she has previously denied reports she had become engaged to her 23-year-old electrician boyfriend, Leona was seen with  the diamond ring on her finger as she left London nightclub Crystal with former X Factor contestant Ashley McKenzie.

Bride to be? Leona Lewis flashes a ring on her ring finger fuelling rumours that she is secretly engaged and planning to wed boyfriend Lou Al-Chamaa

Looking a little worse for wear, Leona's outstretched hand revealed a shiny ring on her wedding finger which will do little to deflect reports that she is secretly planning to get hitched to boyfriend Al-Chamaa.

Lewis denied reports the couple were engaged last November, but admitted her partner was "the one" and hoped to marry him in the future.

She has said: "Me and Lou are good friends and I think that's the important thing, that we're friends and that we have a laugh together."

Best friend: Leona with boyfriend Lou Al-Chamaa at the launch party for single Bleeding Love last year

Leona has known her electrician boyfriend, Lou, since she was 11, and they have been dating since she was 17.

She credits him with being one of her biggest supporters, and it was Lou who supported Leona at the X Factor auditions.

But she has said: "I'm too young to talk about marriage and kids just yet."

Earlier this year Lewis became the first British woman in 20 years to top the U.S. charts, with her hit song Bleeding Love.

She and boyfriend Lou Al-Chamaa share a flat together in Hackney.

Leona and footballer David Beckham are set to star in the spectacular closing ceremony at the Beijing Olympics.

X Factor winner Leona, will sing to an estimated global audience of over 150million.

And Becks, 34, will fly in from Los Angeles to play a leading part in the performance - designed to get the world excited about the 2012 event.

A London 2012 source said: "Leona and Beckham have accepted the invitation to sprinkle some stardust on the show.

"They epitomise what London 2012 is about. Leona is a young global star from London who has risen from nothing."