The Industrial action - which came after Andy Gilchrist, the FBU general secretary, said his members were offered a worse pay deal than in November - could coincide with military action in Iraq.
The ruling executive of the Fire Brigades Union is likely to by considering new walkouts in the six-month dispute.
The dispute now enters a critical phase following months of failed negotiations and a series of strikes that saw military Green Goddesses rolled out to provide emergency cover.
Army resources will be stretched during any conflict in the Middle East, making it difficult to commit thousands of troops to provide emergency cover for striking firefighters - and risking a political and public backlash for the FBU executive.
But speaking to reporters, Mr Gilchrist said it was not certain that war, or the UK's involvement in it, was inevitable.
He said his union's concern remained firefighters.
The rejected deal consisted of a "final" offer of 16% over three years linked to changes in working practices.
The FBU had warned there would have to be "significant" changes to the offer to make any progress in the dispute.
But local authority employers made clear that no new offer or document would be given to the FBU today.
"The only thing we have agreed to do is give an explanation, but there will be no changes to the wording of the offer. We are incredulous about FBU claims that there will be a new offer," said a spokeswoman earlier.
Employers' sources said the union was trying to change the wording of a section covering conditions of service, from management determining the duty systems after "consultation" with staff to "agreement" with staff.
Employers said the section was "absolutely crucial" because they felt it transferred power away from the union. "It is the cornerstone of what modernisation is all about," the spokeswoman said. "It is misleading to claim there will be a new offer or proposal tabled."
The union's executive spent just three hours last week throwing out the 16% pay offer, complaining that "strings" attached to the deal would worsen conditions for firefighters.
