Those in the firing line include Susannah Constantine and Trinny Woodall, the 'What Not to Wear' presenters who are currently appearing in a major campaign for Nescafe. Others include members of the 'EastEnders' cast and 'The Kumars at No 42', who appeared in a recent Walker's crisp ad.
News and current affairs presenters and journalists have already been forced to give up lucrative work -- now stars from other shows might have to give up big money ad contracts as well.
The BBC has strict guidelines on the kind of promotional work that presenters on its programmes can undertake. The rules state: "In certain cases, the commercial value an artist can derive arises largely from the prominence achieved from their connection with BBC programmes. We must ensure that these associations are not exploited inappropriately."
In the Nescafe ads there are explicit references to Woodall and Constantine's roles as fashion commentators.
Last year Linda Barker had to give up her job as an interior decorator on the BBC television show 'Changing Rooms' in the wake of her new-found role as the face of Currys and sofa company DFS.
The Conservative Party has called for the BBC to make sure its guidelines are working.
Julie Kirkbride, the shadow culture spokesman, told the Sunday Telegraph: "The BBC needs to make sure guidelines for artists are working as effectively as its guidelines for journalists.
"Where people are clearly operating in breach of the BBC's guidelines, the appropriate action should be taken in line with those rules."
The call was echoed by the Liberal Democrats, whose culture spokesman Don Foster stopped short of criticising individuals.
"It is important these guidelines are followed. I am not going to criticise any particular individuals but it is important the BBC takes a tough stance on this issue to ensure public trust is not undermined," he said.
The BBC says that the current campaigns all fall within its guidelines.
A BBC spokesman said: "We do not want to unreasonably restrict what our on-air talent does as long as it does not undermine their own role or the reputation of the BBC."
However, the latest cases mirror that of Channel 4 'Countdown' co-host Carol Vorderman, who was sacked by the BBC as presenter of popular science show 'Tomorrow's World' in 1995 when she appeared in an ad for Ariel Future. Then the BBC claimed the scientific context -- she appeared in a white coat -- compromised her integrity.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the Forum here.