The Mayor of London has been accused of “playing games” over underground lift closures after a series of problems at an Enfield station.

The lifts at Oakwood station on the Piccadilly Line have been closed on 20 separate occasions this year due to “non-availability of staff”, and 40 times since 2012.

The 2015 closures all took place between 24 July and 22 August.

In its longest consecutive period, the lifts were closed for over 10 hours, between 18 August at 3.04pm and 19 August 1.25am.

In a written answer to a question about lift closures, Mayor Boris Johnson said that the problems were exceptional this year due to a staff overtime ban. However Mark Morris, of the Liberal Democrat London Assembly Group, said that it was a long-term issue.

Mr Morris said: “There have been recurring problems with the lifts not operating due to a lack of trained staff for many years.

“The Mayor and TfL are also playing games with figures by claiming that across London the problem of lifts closures is improving. While the number of incidents of lift closures due to a lack of staff might have fallen, the actual hours of closures has been increasing.

“Looking ahead, if however more TfL staff are trained hopefully lift closures due to lack of trained staff will really fall. It might take a year, but hopefully the problem will be largely end in the future.”

In his answer Mr Johnson had called the closures “infrequent and usually of a short duration”.

Responding to a question set by Lib Dem London mayoral candidate Caroline Pidgeon, Mr. Johnson said: “At Oakwood station specifically, London Underground unfortunately had to close the lifts 20 times. This was due to a staff overtime ban that was taking place at this time. This ban has now been withdrawn and, since 22 August 2015, they only had to close the lifts at Oakwood station once.

“The customer services modernisation programme is ensuring that staff are more visible and available to assist customers at stations across the Tube network. It includes a training programme for all station staff.

“The programme specifically covers accessibility training, and will help ensure there are sufficiently trained staff in place at stations, with licences to manage lift operations.”

Since 22 August, lifts at Oakwood have been unavailable once, when a staff member took last-minute compassionate leave.