TUC general secretary Brendan Barber has warned the potential 'super-union' not to turn its back on the TUC after merging.
Speculation is growing that the super-union will supersede the TUC, which has been criticised for being too close to the Labour government. But Barber said that while he could see the benefits of merging the Transport & General Workers Union (T&G), GMB and Amicus unions, the TUC was still best placed to speak for all staff.
The three unions are due to join forces in January 2007, creating a body with a total membership of about 2.6 million.
Speaking ahead of this week's TUC Congress in Brighton, Barber admitted that the merger would "change the landscape" of British unionism.
"But I hope it won't be at the expense of relations with other unions and the crucial role of the TUC as a single, coherent union voice," he added.