A planned six-day strike on London Underground was condemned by Transport Secretary Philip Hammond in Parliament today.
Members of the Rail Maritime and Transport (RMT) union will walk out later this month and in June, threatening travel chaos for millions of passengers.
Mr Hammond said the strikes were "highly irresponsible" and warned the union they would only lead to "tougher industrial relations laws".
At Commons question time, Tory Greg Hands (Chelsea and Fulham) asked: "Will you join me in condemning the proposed six days of tube strikes by the RMT next month over only two individual employees as both obscene and irresponsible?
"And also Labour's candidate for London mayor (Ken Livingstone) who has singularly failed to condemn the action, and indeed his deputy (Val Shawcross) who even appears at RMT protest meetings?"
Mr Hammond replied: "I absolutely agree with you. This series of strikes is highly irresponsible.
"No one in this Government is spoiling for a fight with the unions but the unions appear to be spoiling for a fight with London.
"I say to the RMT and other unions that this kind of irresponsible strike action, where an alternative, proper remedy - there's an employment tribunal ongoing - is available, this is only strengthening the hand of those including the mayor who are calling for tougher industrial relations laws."
The RMT said around 1,500 Tube drivers will walk out for between nine and 24 hours from Monday May 16 to Friday May 20 and again from Monday June 13 to Friday June 17.
The move follows a 2-1 vote in favour of industrial action by RMT members in protest at the dismissal of Northern Line driver Eamon Lynch and Arwyn Thomas, a Bakerloo Line driver. Both men have taken a case of unfair dismissal to an employment tribunal.
Commons Leader Sir George Young, a former transport secretary, also criticised the RMT.
During questions on future Commons business, Sir George said: "This Government is not seeking to pick a fight with the trade unions. We have no plans to introduce fresh legislation on employment laws, but we do keep the matter under review.
"I very much hope trade unions will not resort to strike action until every other opportunity has been examined.
"In this particular case, I am not convinced they have done this."
Bob Crow, general secretary of the Rail, Maritime and Transport union, said: "It is clear that there is now a concerted attack being mobilised by the hard right of the Tory Party that would attempt to impose a form of twisted democracy on the RMT and the trade unions that would mean that the vast majority of politicians, including London Mayor Boris Johnson, would not have been elected if the same rules applied.
"RMT secured a two to one vote for action on a 46% turnout in this latest ballot - higher than the turnout in the 2008 mayoral election and streets ahead of the Euro elections and every set of council elections in living memory.
"We are also watching with interest the turnout in today's AV vote - will Boris and his crew try and overturn that if it fails to hit 50%?
"This is simple class war and a return to form for the old-school Tory right - one form of democracy for the political class and another for the working class fighting to defend jobs, services and their victimised colleagues."