London Underground Director Richard Parry said: "The changes we are proposing are vital to ensure we can deliver a safer, more frequent Tube service in future. We are committed to customer service and to protecting London Underground's excellent and improving safety record.
"The threat of strike action by the RMT is unjustified and kneejerk at this very early stage of the consultation process. Their members will be best served by meaningful discussion not strike threats.
"We have made it clear from the very beginning that all stations will continue to be staffed at all times, all stations with a ticket office will continue to have one and there will be no compulsory redundancies.
"The huge success of Oyster means the use of ticket offices has fallen by almost 50 per cent. Just one in 20 journeys now starts with a visit to a ticket office. The proposed changes to ticket office opening hours would enable us to deploy our staff in those places at those times where passengers need them most – on stations, not behind glass screens or in back of office roles.
"Like any public service, we have to be as efficient as we can, particularly in the present difficult economic times to deliver value for money for the farepayers and taxpayers who fund the Tube."