One in 50 male offenders in prisons are self-identifying as transgender, according to a survey by the official jail watchdog, amid concerns inmates may be attempting to secure extra perks.

The figure, the first by the watchdog, suggests there are up to 1,500 transgender inmates among the 90,000 prisoners in England and Wales, more than ten times previous estimates, and at least four times the number in the general population.

Among offenders from traveller communities the number self-identifying as transgender or transsexual rose to one in ten inmates, according to the annual report by Peter Clarke, the chief inspector of prisons.

Transgender prisoners are entitled to shower alone, separate cells and can apply to switch between male and female jails. Earlier this year the Ministry of Justice created a "wing" for transgender prisoners to keep them away from other inmates.

Mark Fairhurst, chair of the Prison Officers Association (POA) said there “would always be some trying to abuse the system” but it would not affect officers approach to treat transgender inamtes with respect and dignity.

Harry Fletcher, director of the Victims’ Rights Campaign, said he was convinced that “for some this is a total try-on” with the prospect of a more relaxed regime.