Firefighters have rejected a 2% pay offer, saying it included a "whole host of strings".
Members of the Fire Brigades Union were consulted on the proposed deal, which broke the Government's cap on public sector pay.
The union said a lack of clarity in the employers' proposals, uncertainty about funding arrangements and concerns about the details of some new areas of work all contributed to members deciding not to accept the offer.
Matt Wrack, general secretary of the FBU, said: "Firefighters, along with all other public sector workers, have suffered hugely as a result of the Government's pay policy.
"The offer fails to clearly address the pain our members have experienced as a result of years of falling real wages."
Mr Wrack added: "The union is deeply concerned that a lack of detail on how the offer would be funded has led to the rejection.
"If a pay rise is funded through cuts to frontline fire services and job losses, this is clearly unacceptable.
"The failure of a number of fire and rescue services to address operational, safety, training and welfare concerns that firefighters participating in trials have raised is deeply worrying."
Firefighters are taking part in trials of emergency medical responding (EMR) and other, new work.
As part of the consultation, each union branch held a meeting where members were asked to vote on whether to accept the pay offer and continue with trials while funding was being negotiated or to reject the offer and consider other options.
The offer included an immediate 2% increase and 3% from next April, subject to new areas of work.
Mr Wrack said it was totally unclear how the pay rise would be funded.
The news follows a Government announcement on Tuesday of pay rises above its 1% cap for police and prison officers.
Unions expressed anger that millions of nurses, teachers, civil servants and other workers were still having their pay held down.