Firefighters will launch a series of fresh strikes over the Bank Holiday weekend, with its long-running dispute over pensions remaining deadlocked.
Members of the Fire Brigades Union (FBU) in England and Wales will walk out for five hours from noon today, between 2pm tomorrow and 2am on Sunday, and between 10am and 3pm on Sunday, forcing fire authorities to make alternative arrangements for fire cover.
The union said the strikes could be halted immediately if the Government made a revised pensions offer that "takes the evidence into account".
Matt Wrack, FBU general secretary, said: "It is purely the failure of the Government to present revised proposals that has led to these strikes. Now the Government is walking away from talks. It is utterly irresponsible.
"The FBU has never walked away from discussion and our members have been patient and measured in their approach, but we will not simply stand by while Government imposes a pension scheme that is totally unworkable, unaffordable, unsustainable and unfair."
The union said firefighters are having to pay higher pension contributions, face working into their late 50s before retiring and could be sacked because their fitness declines as they get older.
"This shows the executive is not serious about finding a resolution for its members.
"The Government is clear that further change can be made through constructive engagement, but not under the shadow of industrial action, which only serves to damage firefighters' standing with the public.
"The deal on the table gives firefighters one of the most generous pension schemes in all the public sector, and the proposals protect the earned rights of a higher proportion of members than any other public sector scheme.
"Nearly three-quarters will see no change in their pension age in 2015.
"Under the new scheme, a firefighter who earns £29,000 will still be able to retire after a full career aged 60, get a £19,000 a year pension, rising to £26,000 with the state pension.
"An equivalent private pension pot would be worth over half a million pounds and require firefighters to contribute twice as much.
"This weekend public safety is our prime concern and robust contingency plans are in place to keep people protected."
Fire chiefs in London urged people to take extra care with barbecues over the weekend, as they finalised their contingency plans.
There will be 27 fire engines on standby in the capital for emergencies including house fires, road accidents and collapsed buildings.
A fire engine may not be sent to less urgent and non life-threatening incidents such as rubbish fires, animal rescues, flooding and people stuck in lifts.
A separate row broke out in Buckinghamshire, with the union accusing the fire authority of "locking out" firefighters for an entire shift even though some of the walkouts are for five hours.
FBU official Steve Allen said: "Local firefighters are extremely worried about the implications of this nonsensical and unnecessary decision."
The union warned the action risked escalating the dispute across the country.
The fire service denied that anyone was being locked out, saying the local authority had decided not to accept firefighters only working part of their shift.