Katy Perry, singer of the hit single E.T. which has sold over 4 million copies, as been forced to cancel two gigs in the U.S. after coming down with "an attack of food poisoning leading to severe dehydration", according to MTV.

The gigs, which would have been held in Chicago on the 8th July and St Pauls on the 9th, have been postponed until the 21st and 23rd August respectively. Perry sent a message out to disappointed fans from her website, "I apologise to my fans in Chicago and the Twin Cities for not being able to perform this weekend, but I am going to return in a few weeks to give them the very best show ever!" The artist, who's album Teenage Dream has already spawned four #1 hits, including including "California Gurls", "Firework", "E.T." and "Teenage Dream", also used Twitter to reassure fans, "Chicago and St Paul - I'm so sorry to have to postpone today and tomorrow's shows," Katy wrote. "But I'll be back."

The California Dreams tour hits the UK in October with dates all across the country including Sheffield, London, Liverpool, Cardiff, Belfast, Birmingham, Newcastle, Aberdeen, Glasgow, Manchester and Nottingham.