Tube drivers will hold 24-hour strikes on four days, including Boxing Day, in a row over pay, a union has said.
Aslef balloted its 2,200 members over demands for triple pay and a day off in lieu for working on the bank holiday.
Staff will walk out on Boxing Day, 16 January, 3 and 13 February. Aslef said 92% voted for industrial action, but Tube bosses said 42% voted to strike.
London Underground (LU) said it had asked the union to abandon its strike threat over "an outrageous pay claim".
Services were severely disrupted last year when drivers walked out on Boxing Day after talks collapsed.
'Quality time off'
The union said it wanted "adequate compensation" for working on Boxing Day and it wanted Tube drivers to be able to volunteer to work on such an "unsociable" day.
A statement from the union said: "The whole dispute has been about seeking equitable quality time off for our members but recognising those who do operate the service may need to be incentivised.
"The company is currently offering no additional payments for working on Boxing Day. The union says its members may need 'substantial incentives' to volunteer.
"If the dispute is not resolved, the union intends to take further action on 16 January and 3 and 13 February."
LU said Tube workers already "earn a premium" for working on Boxing Day.
A spokesman said an agreement in 1992 specified drivers would earn about £44,500, work a 35-hour week and have 43 days' leave.
As part of the agreement, Tube drivers have to work some public holidays, including Boxing Day.
LU said it had reduced the number of drivers needed to work on Boxing Day after Aslef raised the issue in 2010 and only a quarter of the 3,500 were needed on the day.
Howard Collins, LU's chief operating officer, said: "It is disgraceful for the Aslef leadership to threaten strike action while we are engaged in continuing discussions on this issue.
"LU has a long-standing agreement with all of its trade unions which cover staff working arrangements on bank holidays, and Boxing Day is included in that agreement."
A spokesman for Mayor of London Boris Johnson said: "It is appalling and simply wrong that at a time when many Londoners are enduring a decline in salary in real terms and rising living costs, that the union are asking for more money for something already included in their salaries.
"These demands would cost Londoners millions of pounds and divert funds from crucial improvements to the transport system."
London Liberal Democrat mayoral candidate Brian Paddick said: "The fare-paying public, many of whom are on minimum wage, who need to get around London, won't understand, let alone sympathise with the unions in this dispute.
"Everyone should be doing their bit to protect the poorest from the worst effects of the current economic crisis, including the trade unions."
Colin Stanbridge, chief executive of the London Chamber of Commerce and Industry, said: "Retailers have already had one of their toughest years with recent sales figures showing a decline year on year fuelled by poor consumer confidence, rising unemployment and mild weather.
"The last thing they need now is disruption on Boxing Day, one of their most important trading dates."