The Daily Star alleges the contestant is an ex-detective constable "who played a key role" on the Jimmy Savile abuse inquiry.
Police have warned Big Brother broadcaster Channel 5 over the risks of having a former police officer as a contestant.
Scotland Yard said it had contacted the television station after the Daily Star claimed a detective constable who it says "played a key role in Operation Yewtree" - the investigation into Jimmy Saville - will be appearing on the show.
Scotland Yard said it had made the broadcaster aware of "potential risks" to ongoing police investigations and reminded the company of its "responsibility".
The new series of Big Brother kicked off last night.
The 16 contestants headed into their new home for the coming weeks as Channel 5 launched yet another series of the show.
The house mates include a former porn star, a plus-size model and a one-time LA gang member.