NHS England has affirmed the rights of trans people to be treated within 18 weeks of referral – despite growing backlogs in the system leaving some waiting years.

Transgender people recently trying to access gender identity services in the UK have reported lengthy waiting times, with one trans woman facing a wait of 21 months for genital surgery alone.

However, after the country’s former top gender surgeon warned that backlogs are “spiraling out of control” – the health body has admitted in a letter to Healthwatch England that it is falling well short of its 18-week target.

It was previously unclear whether the 18-week target for all treatments applied to gender services, but the letter released this week clearly states: “NHS England agrees that the people accessing gender identity services have a legal right under the NHS Constitution to be seen within 18 weeks of referral.”

The body – which replaced regional Primary Care Trusts in 2013 – says it “inherited a limited understanding of the scale of the problem” from its predecessors, claiming there was “no standard or consistent process” for collecting data about gender services under the regional bodies.

It continues: “The limited data that we have recently secured from providers leads us to believe that there are two issues in the supply of gender identity services, that of entry into the service via first appointment and that of waiting times for surgery.

“We are working to understand the scale of both of these issues and we aim to generate scenario based solutions by March 2015.

“As part of this work we will be working closely with gender identity clinics to understand the internal processes and possible bottlenecks from first referral to referrals for surgery.

“The outcome of this work will enable us to consider the provision of a more equitable service that aims to meet the 18 week Referral to Treatment standard.

“Area teams have been asked to initiate discussions with providers as a matter of urgency about potential options to expand capacity and, following the SCOG decision referred to above, progress with moving towards and sustaining the standard will be the subject of routine performance and exception reporting.”

A statement from trans group UK Trans Info said: “UK Trans Info has campaigned for many months to get NHS England to acknowledge that patients have the legal right to access gender identity services within 18 weeks of being referred by their GP, and then later to access surgery within 18 weeks of being referred by their GIC.

“There have been repeated claims from NHS organisations that gender identity services are exempt from this legislation, but our position has consistently been that these organisations are incorrect in their understanding of the legal position.

“UK Trans Info welcome that NHS England have finally accepted the true legal position.

“We recognise that it will not be quick or easy to bring the excessive waiting lists back down to within legal limits, but the first step to fixing a problem is to acknowledge it’s existence.”