A hospital in England has said it will no longer take in patients from Wales except for in emergencies or maternity cases.
The decision at the Countess of Chester Hospital is thought to impact thousands of people in Flintshire.
It means GPs will be unable to refer them for treatment over the border - and could have further impact on pressures at hospitals across north Wales.
In a statement, the hospital said, "We will be unable to book new routine elective care appointment for patients living in Wales."
"This situation will have no impact on patients who already have an appointment with us and it will not affect our urgent care services, including A&E. Any patient living in Wales who presents to A&E will be seen as normal."
The board's Chief Executive said the "difficult decision" was made due to "unresolved funding issues". She said it had been taken with "great reluctance".
In a statement, The Royal College of GPs said it is a situation which "fails to put patients first".
"This is a situation which fails to put patients first and we are calling on the Welsh Government together with BCUHB to work with The Countess of Chester Hospital NHS Foundation Trust to find a constructive solution as quickly as possible."
The Welsh Government also issued a statement saying limiting access for Welsh patients on financial grounds are "unacceptable"
"This is not a decision taken by Welsh Government. Any actions taken by English providers to limit access for Welsh patients on financial grounds are unacceptable and not in the spirit of reaching a cross-border agreement with English NHS representatives.”