Health bosses have refused to support a large mental health service becoming a foundation trust due to a number of "quality concerns".
Sutton Clinical Commissioning Group (CCG) does not support the Tooting-based South West London and St George’s Mental Health NHS Trust taking the step towards independence from central government.
Sutton is the only CCG to refuse the trust, which serves Sutton, Richmond, Merton and Wandsworth, in its application.
They have outlined a number of issues including concerns about the implementation of its review into Sutton’s Child and Adolescent Mental Health Services (CAMHS).
Recently it was revealed father Jason Clark, 45, whose daughter Leah, 16, has used CAMHS since she was diagnosed with autism eight years ago, raised a number of concerns about the trust.
These include the replacing of experts, such as psychologists, with junior nurses, centralising staff, and a lack of consultation with parents.
David Bradley, chief executive of South West London and St George’s Mental Health Trust, said: "By becoming a foundation trust, our members and governors will be able ensure we are meeting the needs of the community and hold us to account if we are not.
"We’re working closely with our partners at Sutton CCG to address their concerns and raise the profile of mental health and well-being."
A spokesperson for NHS Sutton CCG said: "We understand that the trust will be disappointed with our decision but we have not been reassured that the trust has addressed the issues that the CCG has raised or fully explained the impact of their Integrated Business Plan on services in Sutton. However, we will continue to work with the trust on our areas of concern with regard to their foundation trust application."
Sutton CCG has also raised concerns about the trust’s Crocus Ward, which treats elderly people, in Springfield University Hospital in Tooting, and action has since been taken.