NHS England has 14 days to respond to the warning.

The Equality and Human Rights Commission (EHRC) has warned NHS England that they need to offer fertility treatments to transgender patients, or they could face legal action.

In a pre-action letter to NHS England, the EHRC warned that “outdated” policies meant that transgender patients were not offered the chance to have their eggs or sperm stored even though transitioning can cause fertility loss. The letter also said that it could lead to a judicial review if step weren’t taken to offer the treatments.

Speaking to the BBC, Rebecca Hilsenrath, the chief executive of the EHRC said: “Our laws and our values protect those who seek treatment for gender dysphoria.

“This means that where appropriate, treatment should be made available in order to ensure that access to health services is free of discrimination.

“A choice between treatment for gender dysphoria and the chance to start a family is not a real choice. We have asked NHS England to reflect on the true breadth of their statutory mandate and the impact on the transgender community of these outdated policies.”

Related: UK Government launches enquiry into the NHS failing LGBTQ patients

However, NHS England said that the EHRC had “misplaced its fire”, and that it should be targeting the government. An NHS spokesperson said: “Decisions on which services are commissioned by NHS England are taken by ministers based on advice from an independently-chaired panel of health experts and patient representatives, using a process set out in primary legislation.”

However, the EHRC’s letter has received considerable support. Speaking to The Guardian, Paul Twocock, the director of Campaigns for Stonewall, said: “We welcome this challenge from the EHRC.

“It’s vital that trans people have fair and equal access to fertility treatment, and for many that should include the option of storing of eggs or sperm before medical transition.”

Meanwhile, Lui Asquith, from the transgender rights supporting charity Mermaids, said: “Currently, the NHS offers little signposting and assistance to [those] wishing to preserve their fertility prior to necessary gender-affirming treatment, despite it being a well-documented, funded option offered to patients about to undertake other life-enhancing treatments that may impact fertility.

“Many young transgender people and their families continue to be faced with the difficult and unique decision to delay often life-saving, gender-affirming treatment while they negotiate fertility preservation via the NHS or privately, or proceed in the knowledge that they may never have a biological family of their own.

“Mermaids stands with EHRC in asking for this disparity in approach to be rectified by the NHS to ensure that everyone, whatever their gender identity, can access healthcare without discrimination.”