The BBC told professor Brian Cox that he could not film alien life if he discovered it - because it would breach health and safety regulations.
The presenter of Stargazing Live was told not to point a radio telescope at a newly discovered planet just in case something was living on it.
The incident occurred during last year's series, when a new planet called Threapleton Holmes B was found.
Speaking to Shaun Keaveny on his BBC 6 Music breakfast show, the scientist said: "Last year when we discovered Threapleton Holmes B we decided to point the Jodrell Bank telescope at it and listen. No one had ever pointed a radio telescope at it. You never know!
"The BBC actually said: you can't do that. We need to go through the regulations and health and safety and everything, in case we discover a signal from an alien civilisation.
"[I said], you mean we would discover the first hint that there is other intelligent life in the universe beyond Earth, live on air, and you're worried about the health and safety of it?!
"It was incredible. They did have guidelines. Compliance!"
The former D:Ream keyboardist also said that bosses at the BBC did not fully understand quite how important the discovery of alien life might be.
"We were thinking of doing something about Mars," Cox continued. "There are lots of maps of Mars and lots of things people can do that computers can't. We were thinking of looking for signs of geological activity which might point to life on Mars.
"Someone from the BBC said to me, would there have to be a prize if someone discovered it? [I said], what do you mean? You're going to say to someone: you discovered the first evidence for alien life beyond Earth - and here's a book voucher as well? You think that's going to make it better? Nectar points?"
A spokesperson for the BBC dismissed Cox's comment, saying they followed a number of jokey conversations about aliens. "In making the series there were many light hearted conversations, one of which was about how different organisations might react to the discovery of alien life," they told IBTimes UK.
Cox's revelations about the BBC's policy on alien life come after an Indian newspaper reported there have been over 100 sightings of a UFO hovering over the country in the last three months.
Scientists in Cambridge are also building a telescope that will be able to search for alien life.