NHS patients in a Hampshire town have been told they cannot change their GP until April because of safety concerns.
Fareham and Gosport Clinical Commissioning Group (CCG) has imposed the ban after more than 2,100 patients recently switched surgeries.
Many have left the Willow Group of practices after problems over access to appointments, the BBC understands.
The CCG said it was worried that popular surgeries would not be able to cope with demand.
It said two of the town's eight GP practices had already closed their lists to new patients.
Dr Andrew Holden from the group said the situation posed "considerable risks".
"If more practices suspend patient registrations, then people moving into the area may not be able to find a doctor at all, which is unacceptable," he said.
"We are also very mindful of practices' concern that they could have a list size that is unsafe to manage."
'Not fit for purpose'
Gosport MP Caroline Dinenage, a health minister, said constituents had raised concerns throughout 2018 about the Willow Group, which manages four practices in the town.
She said the complaints were about a lack of appointments and problems with the telephone system.
In an end-of-year letter to patients, the Willow Group said it recognised that access to appointments was "an issue".
The group said it had replaced its old telephone system, which was "not fit for purpose".
It said it was continuing to advertise GP posts and to recruit other clinical staff for the Brune, Forton, Stoke Road and Waterside medical centres, which it has operated since April 2017,
The Care Quality Commission rated the Willow Group sites as "good" after an inspection in December 2017.