US R&B star Alicia Keys has postponed two concerts on her European tour after her doctor told her to rest her voice.

Her publicist Patti Webster said she was spending the next few days off stage due to laryngitis.

Grammy-winning Keys was meant to be performing on Monday in Glasgow and on Tuesday in Manchester.

The dates will be rescheduled. Keys won two Grammys for best female R&B vocal performance and best R&B song at this month's awards, for her single No One.

Despite a rocky start to her recording career, which saw her signed and dropped by Columbia records, her debut album, Songs In A Minor, was a global success.

It sold more than 12m copies, and won Keys five Grammy awards in 2002.

Her latest album, As I Am, has sold millions of copies worldwide.