Selena Gomez has pulled out of all public appearances today (22.05.13) after coming down with a mystery illness.

The 'Come and Get It' singer is in London to promote her new single and while she was able to make a scheduled appearance on BBC Radio 1 this morning, the young starlet has cancelled the rest of her promotional duties for the day after taking ill - although she isn't sure what the cause is.

She wrote on her Twitter account: ''Sorry to everyone for having to cancel today. I am not sure if I am sick or ate some bad food but, I feel horrible. I am going to take the rest of the day and try and get better for tomorrow. So Sorry :( Love you guys. (sic)''

Despite the cold weather and an early start, Selena spent time signing autographs and taking photos with fans outside Radio 1 headquarters in west London this morning before her sickness set in.

The 20-year-old beauty jetted into gloomy London yesterday (21.05.13) after wowing audiences with a performance of her new single at the Billboard Music Awards in Las Vegas, Nevada on Sunday (19.05.13).

The actress-and-singer turned heads in a provocative gold bodice which bared her cleavage and legs as she confidently took the stage with a full troupe of dancers.

Selena was rumoured to have reunited with on/off boyfriend Justin Bieber, 19, at the event but despite speculation that they would sit next to each other, Selena was seated in the audience next to pal Taylor Swift.

However, the lovebirds were spotted sharing a kiss on the cheek backstage.