The launch of the trouble Night Tube service will be delayed, according to sources.

Insiders have told reporters that the projected 24-hour service on five London Underground lines, including the Jubilee, are no longer feasible while rosters are in dispute. The expansion was due to start on September 12.

Transport for London have not confirmed the reports.

The news comes as three unions – TSSA, Unite and RMT – are preparing to strike on two days in August after talks with management at conciliation service Acas broke down.

Aslef is considering its position but has indicated it might join the strike, the first fracture in the union action.

A delay has been widely touted. Back in July, as The Wharf first reported, Mayor of London Boris Johnson was backing away from the September 12 date, saying: “I can’t say exactly what date it is and I don’t particularly care but we’ll get it through this autumn.”

The latest announcements from unions and management have revealed that there is little progress not only on resolving the dispute but what the actual dispute is about.

The unions say they are not concerned about pay but about “work-life balance” calling LU's projected working arrangements “rosters from hell”. LU managing director Nick Brown said the unions were after more money.

Canary Wharf workers leave the estate early on Wednesday

Mr Brown said: “We are not going into it lightly, we have given many assurances and after the first dispute we reshaped the content of our offer to take on board the work-life balance issues the unions raised.

“But now they have pulled it back to actually asking about money and the lie to that statement is given by the fact they demanded more money on Monday night.”

RMT General Secretary Mick Cash said its members had “made it clear that they are determined to protect their work-life balance and not fall into a trap where they will be forced to wreck their home lives in order to comply with the ‘rosters from hell’ which have been drawn up to plug the staffing gaps in the night Tube plans”.

Leader of the London Assembly Labour Group Len Duvall AM said: “By speculatively announcing a start date without any consultation with the people expected to run the service Boris Johnson’s gung-ho approach has led to disputes, disruption and now delay.

“It’s been clear for a long time that the problems facing the Night Tube would not be easily overcome so in a sense a delay isn’t a major surprise. I hope this delay will provide the breathing space necessary for unions and management to sit down and negotiate a resolution to this dispute without the need for further disruption to passengers.

“From the outset Boris Johnson has treated the Night Tube as more of a publicity stunt despite it being a deeply complex project.”

Rail unions are planning to walk out for 24 hours from 6.30pm on Tuesday, August 25, and at 6.30pm on Thursday, August 27.