Natalie Imbruglia and will.i.am get romantic

Natalie Imbruglia and will.i.am kissed in a London nightclub over the weekend.

The Australian beauty and the Black Eyed Peas rapper, both 33, seemed oblivious to onlookers – including celebrities Sienna Miller and Jesse Metcalfe – as they got to know each other intimately during a night out at Monroe's nightclub at No 5 Cavendish Square.

A source said: "It was a very drunken night in one of the private VIP rooms. A few models and the stars got through a number of magnums of champagne and vodka.

"Natalie and Will were getting on really well, and there were some surprised looks when they started kissing. Sienna made her excuses and left fairly early, but the others stayed until 7am."

It is not known if the misty-eyed pair left together.

Natalie – who announced she was splitting from husband Daniel Johns in January after five years of marriage – has been romantically linked to Razorlight frontman Johnny Borrell and British business tycoon Richard Branson's son Sam.