The singer has been officially dating Jason Trawick since May last year.

Britney was photographed wearing the large diamond ring on her wedding finger in London on Sunday.

She waved at fans and deliberately held up her hand to show off the huge rock. The star is in the UK to film the video for her new single Criminal.

Britney will then continue on the European leg of her Femme Fatale tour.

The 29-year-old has been married twice before.

She filed for divorce in 2006 after having two children, Sean Preston and Jayden James.

Her current boyfriend Jason is a talent agent and he was seen visiting an up-scale jewellery store in Los Angeles this week, which first sparked the wedding rumours.

However, Britney’s spokesperson has denied any knowledge of an engagement. Her representative insists Jason was discussing 'other matters' with jeweller Pascal Mouawad.