Lily Allen has been spotted wearing an engagement ring.

The 24-year-old 'Not Fair' singer was seen enjoying a meal at London restaurant Quo Vadis with her boyfriend Sam Cooper, wearing a shining band.

An onlooker in the restaurant told the Daily Star newspaper: "It seemed like they were celebrating something but Lily's smile vanished when she saw the cameras.

"She looked determined not to have her picture taken with the ring on."

However, her spokesperson has denied she is betrothed to Sam, saying: "She often wears a ring on that finger."

Lily has been dating the 44-year-old builder since the summer, and she recently revealed they keep the romance alive in their relationship by taking mini-breaks in Europe.

She said: "If I'm on tour in Europe, Sam will fly out on a Friday night when he's finished work and stay with me for the weekend and then fly back on a Sunday. We talk to each other two or three times a day."

Lily recently claimed she was taking a two-year break from the music industry to focus on a fashion career.