Conservative MP for Saffron Walden, Kemi Badenoch, has apologised after admitting she hacked a Labour MP’s website to “say nice things about the Tories”.

Mrs Badenoch made the confession in a video by Core Politics, which was obtained by the Mail on Sunday.

Asked what was the naughtiest she’d ever done, the 38-year-old replied: “About 10 years ago I hacked into a Labour MP’s website and I changed all the stuff in there to say nice things about Tories.

“This was a foolish prank over a decade ago, for which I apologise.”

Tom van de Bilt, secretary of Saffron Walden Labour Party, said the matter should be “urgently investigated”.

He said: “What Ms Badenoch has described doing is a shocking breach of the Computer Misuse Act: a criminal offence punishable by custodial sentence.

“Saffron Walden Labour Party call on Kemi to give a full account of who her victim was, when this happened and whether the incident was previously reported to the police.

“The Cambridge Analytica revelations show how vital it is that political campaigns stay within the law. Tory attempts to make light of this as not ‘proper hacking’ because it relied on guessing a password miss the point.

“The seriousness of the offence comes from the effect on the victim and on the reputation of our democracy, not the skill level of the offender.

“Given the current climate of concern around cybercrime, and especially in relation to electoral campaigning, Saffron Walden Labour Party further ask that local Conservatives condemn the hacking of opponents’ websites and urge Conservatives in parliament to withdraw the whip while the matter is urgently investigated.”

Mrs Badenoch did not name the MP, but Labour MP Harriet Harman later tweeted to say she had received an apology from Mrs Badenoch and accepted it.

It was reported in 2008 that Ms Harman’s personal website was hacked and a post apparently announcing her resignation was published.

Tom van de Bilt added: “In accepting an apology Harriet Harman has been gracious in the extreme and I accept her prerogative as the victim if she wishes a line to be draw under the matter.

“However, for Kemi’s constituents this apology will do little to alleviate concerns about her personal judgement a mere two years before first standing for parliament herself; nor does the flippant manner in which she disclosed it give much confidence in her commitment to tackling cybercrime today.

“Failure to discipline Kemi Badenoch, both within the law and through Conservative party procedures, is a green light to illegally disrupt the work of opposition parties in a democracy. It would also show the Conservatives’ ‘respect agenda’ to be empty rhetoric.”

John Lodge, chair of local party Residents for Uttlesford, added: “Why is it always one rule for Westminster politicians and another for everyone else? Kemi Badenoch has a law degree, so when she hacked Harriet Harman’s account she clearly knew that she was not committing a ‘foolish prank’ as she calls it, but a serious criminal offence.

“The former News Of The World Editor Andy Coulson was jailed for 18 months for hacking private accounts. Why isn’t the Crown Prosecution Service stepping in here too?

“This drawing-a-line-under-it-after-issuing-an-apology nonsense just smacks of some secret deal being done behind the scenes between the Tories and Labour - maybe as part of Harriet Harman’s bid to become Speaker of the House.

“This type of behaviour is exactly why voters have been abandoning the traditional Westminster dinosaurs for newer, smaller parties, such as Residents for Uttlesford, who concentrate on local issues, and so benefit residents, rather than playing political power games.”

Mrs Badenoch said: “This was a silly prank that happened ten years before I became an MP. I guessed the password to Ms Harman’s website and logged in.

“I have apologised directly to Ms Harman who very graciously accepted it.”

Under the Computer Misuse Act 1990, unauthorised access to computer material can result in two years’ imprisonment and/or a fine.