The Fawlty Towers creator claims that he was recently sent two "terrible" scripts by the corporation.
Cleese told The Sunday Telegraph: "I was sent two scripts by the corporation which I was initially very excited about.
"But then I read them and they were terrible. It doesn't mean what it once did. They have lost sight of the fact that the script is the most important thing.
"Twenty years ago, there were 30 or 40 great scriptwriters in the UK - most of them at the BBC. Now, there are only seven or eight."
Revealing his explanation for the alleged decline, Cleese added: "Shows are getting smaller audiences, as there are so many channels, so writers are paid less. Perhaps, there isn't the incentive to get into the industry."
> John Cleese: 'Writing is much harder than acting'
> Fawlty Towers: Tube Talk Gold