Tube strike: London Underground deny 'rosters from hell' claim
Union claims of "rosters from hell" on the new night time Tube service are "not true", London Underground (LU) has said.
Members of three unions will stage two 24-hour strikes on 25 and 27 August in the dispute over the proposals.
LU Managing Director Nick Brown said the unions had demanded more money, but unions claim their members wanted to protect their work-life balance.
Talks are due to resume between LU and the unions later.
Members of the Rail, Maritime and Transport (RMT), the Transport Salaried Staffs Association (TSSA) and Unite unions will walk out for 24 hours from 18:30 BST on Tuesday 25 August and at 18:30 on Thursday 27 August.
However, disruption is likely to be felt throughout most of that week owing to the timing of the strikes and the knock-on impact to the service.
The train drivers' union Aslef is yet to decide on the action it will take.
Speaking on Radio 4's Today programme, Mr Brown said: "We are adding 500 extra staff across the network, train operators, station staff, engineering staff, for the night Tube.
"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."
Announcing the strikes on Tuesday, 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".
He said staff were angry Mr Johnson had "ignored" their concerns.
The RMT added that delays on the District Line on Wednesday morning were caused by further industrial action over the night service dispute.
Steve White, operations director for LU, apologised, saying the unions were currently taking action short of strike "which on occasion disrupts the service".
A spokesman for Mayor of London, Boris Johnson, said: "The union leadership appear hell bent on strike action and the mayor is dismayed at their continued failure to put what is a fair, sensible and generous offer on the table to their members."
However, Manuel Cortes at the TSSA said it was "time for the mayor to start getting his hands dirty and get down to serious direct negotiations" to avoid a week of disruption.
Hugh Roberts at Unite said LU's "vague assurances" about work-life balance and unsocial shifts did not give its members "the security they need to plan their home life over the long term".
The 24-hour service is due to be introduced on 12 September.