Unite the union has rejected the latest pay deal offered by Transport for London in the long-standing dispute over pay and working conditions on the proposed Night Tube.
The union, representing 600 Tube engineers and maintenance staff, will continue talks with TfL in an effort to come to an agreement. The union has not ruled out further industrial action over the matter.
Last week, the union rejected an offer of a one-off bonus of £500 to all workers- not just those on the Night Tube - and an agreement that staff will work to a 36-hour four day week.
Unions had originally intended to go on strike last week, however, it was called off at the last minute after the new offer was made.
Other unions are still considering the pay offer.
A strike by RMT staff is scheduled to go ahead this weekend in a separate dispute over ticket office closures. TfL has, however, warned that they will lose the £500 bonus part of the pay deal if they go ahead with the action. Talks on the matter are continuing today.