Emergency ban on prescribing the drugs was put in place before dissolution of parliament last week
The UK government has until Friday to respond to a letter from campaigners who are mounting a legal challenge against the ban on puberty blockers for young people that came into force this week.
The non-profit legal organisation The Good Law Project and the transgender advocacy group TransActual have instructed senior lawyers to challenge a ban on the drugs, which campaigners say could lead to the criminalisation of healthcare providers.