Murray has won two titles in 2008 but is out of the world top 20

British number one Andy Murray has pulled out of next week's Valencia Open after picking up a virus.

The 20-year-old had been expected to open his clay-court season at the event ahead of the French Open in May.

The Scot will now continue training in Spain before returning to competitive action at the Masters Series tournament in Monte Carlo on 21 April.

The illness is a blow to Murray, who was aiming to improve his ranking after dropping to number 22 in the world.

Murray dropped out of the top 20 for the first time since August 2006 after his second-round defeat in Miami at the end of March.

That loss followed defeat in the last 16 to Tommy Haas in Indian Wells.

Murray has won two ATP tournaments to his name this year at the Qatar Open and Open 13 in Marseille.