Sir Alan Budd's investigation into David Blunkett's fast-tracking of a visa application for his lover's nanny has been criticised by the Committee on Standards in Public Life.

Sir Alan's investigation was incomplete and conducted in an "ad hoc" way, the committee concluded on Thursday.

Sir Alastair Graham, chairman of the committee, said: "The Budd inquiry highlighted the need for a clear, well-understood and independent process to establish the facts about an allegation to ensure all parties are treated fairly and issues of legitimate public concern are properly addressed.

"The experience of the manifestly ad hoc way in which complaints were investigated against the then home secretary, suggests that it is time for the government to review its position."