Christina Aguilera has cancelled her US tour.

The 'Dirrty' singer - who was set to tour America with 'Bleeding Love' hitmaker Leona Lewis supporting her - has put the dates back by a whole year just four days after the tickets went on sale, claiming she needs to spend more time on the production.

A spokesman for Christina said: "She felt she needed more time to rehearse."

The 20-date run was due to commence in Connecticut on July 15.

Christina has faced some criticism of late, with many critics saying she has based her comeback look on Lady GaGa, but the mother-of-one recently rubbished claims of a rivalry between the two.

Writing on her blog, she said: "It is very easy for comments to be taken out of context and create unnecessary drama - especially between us women.

"So I would like to tell you all directly so my words cannot be misconstrued to sell someone else's story: I have absolutely nothing against Lady Gaga or any other female artist in this business."

The tour cancellation has also come as a massive blow to British support artist Leona who was due to launch her new album while touring the US.

A source said: "Cracking America was her next big thing this year. Simon has been keeping an eye on how she is launched in the States, so this is a disaster."