The Daily Mail today reports that the Home Office intervened in a Belgian criminal investigation, asking for Labour Party donor Lakshmi Mittal to be allowed to see secret documents relating to a money laundering and bribery inquiry.

A spokesman for the Belgian prosecutors - who rejected the request - said: "In 26 years in the judicial service I have never seen a letter like this. The British Home Office appeared to be acting like a lawyer or personal adviser to Mr Mittal and not like a government department."

The investigation is focussing on corruption surrounding a £39 million pipeline deal in Kazakhstan where £3.5 million is alleged to have been paid in bribes.

The Mail says that four different government departments have now helped Mittal in his business endeavours.

The Home Office initially denied sending the letter but later explained that a request from Mittal's solicitor had been forwarded on to the Belgians, with a request that they help with the questions it contained.