Kemi Badenoch has apologised for carrying out the “foolish prank” before she was elected to Parliament, more than a decade ago.
Ms Badenoch, who was appointed the Conservative Party’s vice chair for candidates in January - made the confession in a lighthearted interview for the online Core Politics channel.
Asked what the “naughtiest” thing she had ever done was, the MP for Saffron Walden, in Essex, 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.”
Ms Badenoch did not reveal the identity of the MP in the clip obtained by the Mail on Sunday.
She told the paper: “This was a foolish prank over a decade ago, for which I apologise.”
It is understood it involved guessing a password on the website.
Tory sources stressed Ms Badenoch was not a candidate or professionally connected to the party at the time.
Ms Badenoch was elected to Parliament for the first time in last year’s General Election.