The Fire Brigades Union (FBU) has rejected a pay offer which would have breached the government's 1% public sector cap, claiming that the proposed settlement was "inadequate" and failed to address the concerns of its 35,000 members.
The development comes after the Fire and Rescue Services National Employers offered to give firefighters a 2% basic salary increase from July 2017 and a potential 3% increase in April 2018, with the possibility of further hikes in 2018, 2019 and 2020.
"We should state from the outset that the Employers' Side shares your view that firefighters deserve to be paid more," said Simon Pannell, the secretary of the National Joint Council for Local Authority Fire and Rescue Services (NJC).
"Developing a longer term deal which builds upon the current position under the joint broadening the role of the firefighter commitment and delivers both greater flexibility within roles and increased pay levels will inevitably take time.
"It is important that both sides of the NJC remain fully engaged in that discussion and that work currently being undertaken through the trials continue."
Unlike the rest of the public sector, pay in the fire service is subject to collective bargaining through the (NJC). Matt Wrack, the general secretary of the FBU, said his members had endured seven years of pay restraint by the government.
"Their real wages are falling and our members are struggling to make ends meet. Firefighters have, in addition, taken on many new roles that are not being recognised in their pay," he said.
"It is sickening to hear politicians praising firefighters for the outstanding work they do every day of their working lives only to be told they have to tighten their belts as a result of economic problems caused by bankers.
"This offer demonstrates that the 1% cap is dead in the water but the offer from our employers is simply not enough.
"It does not recognise the extra work firefighters have been doing, it fails to address their falling living standards and, despite hints at improvements, does not make clear what they will be earning in future years. This offer lacks detail and credibility."
The comments come after Foreign Secretary Boris Johnson, Environment Secretary Michael Gove and Health Secretary Jeremy Hunt spoke out against the 1% public sector pay cap, which was introduced under the Conservative and Liberal Democrat coalition government in 2012.
Number 10 had also admitted that the public were "weary" of the cap, with the Conservatives losing their majority of MPs at the general election. But Downing Street has since maintained that there has been no change in the policy, which was part of the Tory manifesto.
Firefighters, meanwhile, have had to respond to a string of terror attacks in the UK, including Westminster Bridge, the Manchester Arena Bombing and the London Bridge and Borough attack.
London Fire Brigade also said more than 200 firefighters were dispatched to the Grenfell Tower in June. The death toll from the disaster is at least 80 and it is expected to rise, with many others left homeless.