Members of the Fire Brigades Union (FBU) in England and Wales will walk out for 24 hours on 12 June and again for seven hours on 21 June as part of the union's long-running dispute with the government over pensions.
The 24-hour stoppage, which coincides with the start of the World Cup, is the longest to be held in the union's three-year campaign, which has already seen 12 separate strikes.
FBU General Secretary Matt Wrack has accused the fire minister, Brandon Lewis, of burying his head in the sand, saying that firefighters "simply will not give up fighting for their futures".
"Concerns over these unworkable proposals remain as valid and grave as ever, and the government has ignored all the evidence, including its own reports," Wrack added. "Our most recent discussions with government suggest they simply do not have a clue about the work firefighters actually do or the standards firefighters are required to meet.
"It is a difficult decision for us to take strike action, but the only way for us to resolve this unnecessary and costly dispute is for the government to start listening to reason."
Watch: FBU general secretary Matt Wracks speaks at the Future of Fire Conference
FBU officials met the minister earlier this week but no progress was made. The union claimed the government was refusing to publish alternative proposals on pensions which the FBU believes would help resolve the row.In response to the announcement, a spokesman for the Department for Communities and Local Government said: "By disrupting constructive discussions and an open consultation with further strike action the FBU has once again shown the country it is not serious about finding a resolution.
"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.