Kevin Rudd has been admitted to hospital for an operation to have his gall bladder removed but has promised to campaign to help Julia Gillard when he is released.

Mr Rudd's office released a statement this afternoon saying the former prime minister would be happy, upon his release, not just to campaign in his seat of Griffith but across Australia to help Ms Gillard.

Mr Rudd will have the operation later today, the statement says.

"Mr Rudd's doctors advise he is likely to be in hospital for a couple of days before returning home," it says.