The Home Office sought Phorm's opinion on the advice it issued to the public regarding whether the targeted advertising service was legal.

Phorm's controversial service, known as 'Webwise', tracks users' online surfing habits and then delivers relevant adverts. Despite claims by Phorm that it 'anonymises' the information about web users so they are impossible to identify, the service has attracted a number of concerns from privacy campaigners.

According to the BBC, Phorm requested an official stance by the Home Office on its technology in emails sent during 2007. In further emails from January 2008, the Home Office sent Phorm a document with its view on the technology. The message said "I should be grateful if you would review the attached document, and let me know what you think".

In another email, the Home Office thanked Phorm for its amendments to the advice, adding: "If we agree this, and this becomes our position do you think your clients and their prospective partners will be comforted?".

Baroness Sue Miller, Liberal Democrat spokeswoman on Home Affairs, told the BBC: "The fact the Home Office asks the very company they are worried is actually falling outside the laws whether the draft interpretation of the law is correct is completely bizarre" .

"I couldn't be more surprised [that] the very department drawing up policy to protect people's privacy is being that cynical," she added.

"Anything the Home Office now says about Phorm is completely tainted."

However, Phorm's chief executive, Kent Ertugrul, told The Guardian: "This is untrue and misrepresents the way in which the British legal system works" and that "in the United Kingdom it is for the courts to decide what is or is not legal, not the Home Office".

The Home Office has yet to comment on the matter.

The revelation about the email between the pair comes at the same time as Phorm chose to launch a new website, which is hopes will answer allegations and criticism's that have been aimed at the service.