Commuters have been warned London Underground that driver strikes could cause “severe disruption” to Night Tube services on weekends for the next six months.
RMT union members will walk out on 7 January and will do so overnight from about 8.30pm every Friday and Saturday through to June.
The strikes over new night rosters will affect the Central and Victoria lines.
London Underground has said drivers will only be rostered to work up to four night shift weekends per year.
It also said the new Night Tube rosters included assurances there would be no job losses, workers could swap night shifts and the amount of night shifts was “fair and reasonable”.
RMT general secretary Mick Lynch urged Tube bosses and the Mayor of London to “think again” and warned the strike action could be extended.
Andy Lord, London Underground’s managing director, said: “We’re disappointed that once again the RMT is continuing to push for strike action that is likely to cause further unnecessary disruption.
“We’re calling on the RMT to join us for talks so we can work together to resolve this dispute around roster changes, which mean no job losses and greater flexibility for drivers.
“If these six months of action do go ahead, we will continue to operate as regular a service as possible.”