The watchdog's probe examined two shows presented by former House of Commons leader Sir Jacob Rees-Mogg, and three jointly hosted by former pensions secretary Esther McVey and her husband - backbencher Philip Davies.

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Ofcom said that under the Broadcasting Code, news must be presented with due impartiality and "a politician cannot be a newsreader, news interviewer or news reporter unless, exceptionally, there is editorial justification".

It found there was no "exceptional justification" in the five cases they investigated and the news was "therefore not presented with due impartiality".

GB News has now been put on notice that it could face a statuary sanction if it breaches the rules again, which could involve a financial penalty or having its licence suspended or revoked.

The watchdog said: "We found that two episodes of Jacob Rees-Mogg's State Of The Nation, two episodes of Friday Morning With Esther And Phil, and one episode of Saturday Morning With Esther And Phil, broadcast during May and June 2023, failed to comply with Rules 5.1 and 5.3 of the Broadcasting Code."

It added: "Politicians have an inherently partial role in society and news content presented by them is likely to be viewed by audiences in light of that perceived bias.

"In our view, the use of politicians to present the news risks undermining the integrity and credibility of regulated broadcast news."

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Ms McVey resigned from her role in GB News in November after she was handed a ministerial position in Prime Minister Rishi Sunak's cabinet.

Two months earlier, an Ofcom investigation found she and her husband broke impartiality rules in an interview with Chancellor Jeremy Hunt, because it "failed to... give due weight to an appropriately wide range of significant views".

While GB News has been found to have breached broadcasting rules before, Ofcom noted that this was the first breach of sections 5.1 and 5.3 of the code.

It said that since opening the investigation into the five shows, "there has only been one further programme which has raised issues warranting investigation under these rules".

Ofcom added: "We are clear, however, that GB News is put on notice that any repeated breaches of Rules 5.1 and 5.3 may result in the imposition of a statutory sanction."