Political website The Canary has been found in breach of press regulator Impress's code over an article it wrote about the BBC's Laura Kuenssberg.
In September, the website reported the BBC's political editor was "listed as a speaker" at the Tory Party conference.
The Canary went on to claim it raised questions about her impartiality and the BBC's.
The BBC made it clear she would not be speaking and was at the event "to report impartially for BBC News".
According to press regulator Impress, The Canary "did not correct this significant inaccuracy with due prominence" in an updated version of its article.
It also breached its code by "misrepresenting facts" and "failing to take all reasonable steps to ensure accuracy prior to publication".
The Canary has now published a correction by Impress, the body which was established by press reform campaigners with government backing in 2016.
The correction was required to be published at the top of the homepage of The Canary for 48 hours in the same-sized font as the original article.
No mainstream newspaper or news website has signed up to Impress, opting instead to be regulated by the Independent Press Standards Organisation, or Ipso.