The latest series of The X Factor begins on ITV1 on Saturday
TV talent shows such as The X Factor are guilty of "cheap exploitation" because they do not pay contestants, performers union Equity has claimed.
It is calling for all contestants who reach the final round this year to be paid and have legal status as workers.
The union is to table a motion at the TUC conference next month calling on TV companies to pay talent show hopefuls.
But X Factor producer Talkback Thames has refuted the union's claims, saying Equity rates "do not apply".
The independent production company, which also makes Britain's Got Talent for ITV1, said its shows were talent competitions and were therefore "not employment in their own right".
"Contestants choose to enter to compete for a substantial prize," its spokeswoman continued.
"The shows also give ordinary people an opportunity to showcase their talents and potentially transform their lives."
Last year, Equity accused production company Endemol of not paying contestants on BBC One show The One and Only.
It alleges companies like Endemol and Talkback Thames are exploiting a loophole in minimum wage legislation that means contestants on reality talent shows have no employment rights.
The union has called on them to follow the example of the BBC, which paid contestants in the final rounds of talent shows How Do You Solve A Problem Like Maria?, Any Dream Will Do and I'd Do Anything at Equity rates.
In June, a court in France ruled that contestants on the French show Temptation Island should be treated as employed workers.
Three contestants on the show were awarded 11,000 euros (£9,472) in compensation after the Cour de Cassation decided they were entitled to overtime pay.
At the time the head of its production company, TF1 Production, said the decision would cause upheaval for TV reality shows.
The X Factor returns to ITV1 on Saturday.