Participants in this year's London marathon will run the first four miles for the taxman, Simon Hughes has warned.

A parliamentary written answer to the Liberal Democrat mayoral candidate from the Treasury revealed that sponsorship payments made to charities in exchange for free entry to the race are subject to VAT at 17.5 per cent.

"Charities and their donors in the UK will benefit from a wide range of VAT reliefs and exemptions," said economic secretary to the Treasury John Healey.

"In accordance with the requirements of the EU directives on which UK VAT law is based, sponsorship raised by runners for organisations who have paid for places in the London marathon is free from VAT."