The Speaker, Michael Martin, yesterday told political parties to stamp out "dirty tricks" campaigns being waged between political rivals on the internet.

Mr Martin expressed his "strong disapproval" of such tactics after an MP complained that he had been the victim of "cyber impersonation".

Bob Russell, the Lib Dem MP for Colchester, told colleagues that a website had been set up in the name of Bob Russell MP "but I can assure you that is not I who has done so. Inquiries reveal the web page has been set up by a leading member of a political party - of which I am not a member - in my constituency".

Rather than taking web users to Mr Russell's own website, a search for www.bobrussellmp.co.uk allegedly led directly to the Conservative party's own website.

The Speaker yesterday expressed his "strong disapproval", adding: "I do not expect officers or employees of political parties to seek to register on the internet names of members of other parties with a view to misleading members of the public.

"I expect all political parties represented in the house to take steps to ensure that no such activity is undertaken by them or on their behalf."

Mr Martin's warning came after Mr Russell raised his complaint as a point of order.