Out of hours medical care at Minor Injury Units in Ely and Doddington could be cut during the week with staff facing job losses.
The bases at The Princess of Wales Hospital and Doddington Community Hospital may only operate for out of hours care from 10am to 6pm Saturday and Sunday from October, under new proposals.
This "significant reduction in service" would mean in certain circumstances people in need of urgent medical treatment would instead have to travel to Huntingdon, Cambridge or Peterborough.
Bosses at Herts Urgent Care (HUC) say the cuts would also result in the "loss of some jobs", reduction in hours or redundancy.
A consultation period with staff is now underway - with meetings being held throughout August.
The out of hours service, which is accessed when patients call NHS 111, currently has an on-call doctor on site throughout the week.
But Cambridgeshire and Peterborough CCG assured that the nearest base would be kept open alongside a mobile home visiting service.
In an official document leaked to the Cambs Times it states the move comes as part of "reviewing patient activity and demand at each of the bases".
David Archer, HUC chief executive officer, writes: "Re-deployment of resources during the week from Ely and Doddington bases would be moved into larger, busier bases at Peterborough and Cambridge.
"This revised model has been approved by the CCG, which we feel will have a positive impact on the service."
Out of hours care at North Cambridgeshire Hospital in Wisbech could also be affected, with CCG bosses consulting with contractors in Norwich.
"There are still a couple of outstanding elements that need to be agreed but we hope we can include Wisbech as part of the mobilisation of the new service," Mr Archer adds.
"This is a really big opportunity for HUC and it has only been made possible through the hard work and dedication of every clinician, operational staff member and the local management team who have worked tirelessly to provide a safe and effective service for patients."
The bases at Doddington and Ely are currently open Monday to Friday from 8.30am to 6pm.
In another official document provided to the Cambs Times, Simon Ingate, head of urgent care Cambridgeshire and Peterborough, writes: "I would like to take the opportunity to assure you that we recognise that this is an unsettling time, however it is important that we meet patient demand and provide a safe and effective service."
A spokesperson for Cambridgeshire and Peterborough CCG said: "Patients can only access the GP out of hours service through NHS 111.
"We constantly monitor the use of all our Out of Hours GP services to ensure we meet patient demand which fluctuates all the time, and to ensure the most efficient use of our limited GP resources.
"As a result of this there are times when a GP will not be located at all our bases simultaneously.
"However, the nearest base will be kept open alongside a mobile home visiting service.
"Patients will be advised which Out of Hours base to attend for the earliest appointment by the NHS 111 Clinical advisor or will be given a home visit if appropriate.
"This has never affected the opening hours of the Minor Injury Units."
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