The announcement brings forward plans for industrial action, as before today the next strikes had been scheduled to begin on January 28 and February 1.
The earlier strike was announced following a meeting in London where officials from the FBU had gathered from around the country.
The official spokesman of the prime minister, Tony Blair, responded saying: "We do not believe that a further strike will do anything to help resolve this issue."
Andy Gilchrist, the FBU's general secretary, had said earlier there was every likelihood that the strikes could be brought forward. He said that firefighters felt "betrayed" that they were only being offered a 4% pay rise and claimed that this would be conditional on the loss of 4,000 jobs.
Mr Gilchrist met the deputy prime minister, John Prescott, for an hour yesterday, describing the talks as "useful" but it is clear that a deadlock remains.
The FBU has demanded a 40% pay rise but fire authority leaders have made it clear that they will stick to recommendations in the independent Bain review into the fire service of a 4% rise now, followed by a 7% increase later this year, heavily linked to modernisation.
The offer is set to be tabled next week when talks between the two sides are scheduled to resume under the chairmanship of the conciliation service Acas.
Speaking before the strike announcement, Ian Foulkes, chairman of the union's Merseyside FBU branch, said he believed there was no point in attending talks at Acas unless a better offer was made. "Our employers seem to be in no mood for conciliation."
He added that his members were "very angry" at the lack of progress. "We thought the employers and the government were going to be reasonable and come up with an offer we could talk about but that doesn't seem to be the case," he said.
