Onay Kasab, national lead officer at Unite, said there is the "potential" for strike action in other parts of the country if local authorities cut the pay of public service workers.
Mr Kasab was asked on the Today programme on BBC Radio 4 if the strike action in Birmingham could spread to other parts of the country.
He said: "Well, if other local authorities look to cut the pay of essential public service workers, then there is the potential for strike action spreading.
"That's why different political choices need to be made."
Mr Kasab added: "It's not about doing things more efficiently, I don't think cutting the pay of public service workers is doing things more efficiently.
"If the pay of public service workers is attacked in other local authorities, then we shouldn't be surprised when people take action."
