Talks to resolve the dispute between British Airways and staff at Heathrow Airport have broken down.
Staff are protesting the introduction of a compulsory new electronic 'clocking in' system, and wildcat strike action over the weekend forced the closure of the airport.
Workers say they are worried about how the system might be used and have asked for assurances about shift patterns and jobs.
National officials from the three unions involved, the Transport and General Workers Union, Amicus and GMB, said no decision would be made about holding an industrial action ballot until consultations with workers were held over the next 24 hours.
The unions had also called for a meeting with BA's chief executive Rod Eddington, but claim he refused to meet them.