A 24-hour strike expected to cripple London's Tube network will go ahead from Tuesday evening after negotiations broke down after 20 minutes.
A strike would affect millions of commuters
The Rail, Maritime and Transport union dismissed the talks as a "PR exercise".
Millions of commuters face "severe disruption" and London Underground (LU) is advising them to be home before the walk-out begins at 1830 BST.
It said the strike was "unjustified" as it had put an improved two-year pay offer to the RMT.
LU's chief operating officer Mike Brown said the deal would give workers a pay rise of 3.5% over the next year and guaranteed to reduce the working week by two-and-a-half hours by 2006.
But the union has said the deal has unacceptable "strings" attached and fears 800 job losses and cuts in station supervisors.
It also says moves to make Tube trains run later at weekends could leave its members "stranded".
Buses will be running as usual, but are expected to be busy
LU is unable to say whether the strike will mean limited services, or a complete shutdown of the network.
The RMT says it is the biggest Tube union, with about 7,500 members including drivers and signalling staff.
It is not known if Aslef members will also choose not to cross the RMT picket line.
During Tube-wide industrial action in September 2002 - a joint strike between the RMT and Aslef - only 15 of the 600 drivers showed up for work, effectively shutting down the Tube.
LU has said it will do all it can to keep London moving during the strike, but Transport for London is advising passengers to consider walking.
Mr Brown said some volunteer managers would be brought in to help at "key interchange points and bus stations".
There will be no additional parking in London during the strike and the £5 daily congestion charge will still apply.
Last week the RMT called off a strike on Network Rail, scheduled to coincide with the Tube action, after the company tabled a better offer on pensions.