The government's plans to extend 24-hour weekend tube services to all London underground and overground services have been criticised as a "desperate" pre-election stunt.
In a rare joint statement, chancellor George Osborne and London mayor Boris Johnson confirmed that 24-hour tubes will run on the Metropolitan, Circle, District, and Hammersmith & City lines, as well as the London Overground and Docklands Light Railway (DRL) by 2021.
There are already plans for the Victoria, Northern, Piccadilly, Jubilee, and Central lines to have an all-night weekend service by September 2015.
Osborne and Johnson said the announcement is part of the government's plans to add £6.4bn ($9.8bn) to the London economy by 2030 and create half a million new jobs.
Unions have described the expansion plan as nothing more than a political stunt, and criticised politicians for not considering the impact on transport workers and other requirements.
Mick Cash, general secretary of Rail, Maritime and Transport union (RMT), said: "This announcement has been dropped on London by the Mayor as a blatant pre-election stunt without a shred of consultation with the union. That is a ridiculous way to conduct important negotiations and to unveil major service developments.
"RMT is not opposed to extended running but there are massive issues on staffing, safety and maintenance which have not been addressed and which would need to be signed off by our reps.
"This announcement has been made against the backdrop of a near doubling in assaults on staff, cuts to over a thousand jobs and the axing of guards on London Overground. Night running would mean increased drunkenness and risks to both passengers and staff alike and could only work with substantial increases in staffing right across the board and that means an immediate reversal of the current cuts programme."
Manuel Cortes, leader of the TSSA rail union, described the idea as nothing more than a "desperate and deluded" stunt from Johnson before he leaves his current role to become an MP from 7 May in Uxbridge.
Cortes added: "How he and George Osborne think they can dream up policies in Tory Central Office for the next Labour Mayor to follow when he or she is elected next year is beyond me.
"His Night Tube starting in September will lose millions and is not due to break even for another 18 years. And yet here he is, with another back of a fag packet publicity stunt, trying to get his picture in the London Evening Standard."