Matt Hancock has been told to apologise to parliament after being found to have breached the MPs Code of Conduct.
The former health secretary was found to have committed a “minor breach” of Commons rules by the Parliamentary Commissioner for Standards.
The Committee on Standards said Mr Hancock showed a “lack of attention to the rules” that was “concerning” for a former minister and MP of more than a decade.
The finding related to an investigation into Tory MP Steve Brine over claims he lobbied the head of the NHS on behalf of a firm he received money from.
Mr Hancock sent standards commissioner Daniel Greenberg an “unsolicited” letter about Mr Brine’s case, including the claim his colleague had “done nothing improper” and “should be cleared from any accusation”.
The committee said Mr Hancock’s letter was a breach of the rules as it amounted to a “clear attempt to influence the commissioner’s investigation”.
Mr Hancock “has still not acknowledged his mistake,” the committee said. But it added that the committee “considers this to be a minor breach of the code”.
It said mitigating factors included that Mr Hancock “did not set out to breach the rules” and did not stand to gain personally through writing to the Commissioner. It added that Mr Hancock “did not act with malice”.
It recommended he apologise to parliament and Mr Greenberg with a personal statement in the Commons. It also recommended Mr Hancock attends a briefing on the code of conduct with the commissioner.
Mr Hancock later said he was “happy” to apologise after being found to have “inadvertently” breached the MPs’ code of conduct.
The ex-minister said in the Commons that the committee “found that I did not seek to break the rules, had no prospect of personal gain and acted without malice”.
He added: “However, they recommended that I apologise to the House and the commissioner for this minor breach and underline that respect for the code and the processes of investigating potential breaches of the code is an important and necessary part of the code. I’m happy to do so.”
Mr Hancock has said he is not standing as an MP at the next election and will instead find “new ways to reach people” who are disengaged with politics.
The West Suffolk MP has been paid £45,000 to appear in an upcoming Channel 4 series of Celebrity SAS: Who Dares Wins. Last year, Mr Hancock was one of the final three on reality show I’m a Celebrity...Get Me Out of Here!
He is also being sued by former Tory MP Andrew Bridgen in a row over a tweet.
