Residents fear the hospital's services are being downgraded permanently

Managers at Prince Philip Hospital in Llanelli said the long-term inability to recruit five middle-grade doctors mean that, from 1 September, its casualty department will close to non-999 emergencies from 2000 BST.

People in the town opposed to the move have begun collecting signatures for a petition and are planning a march at the weekend to protest as what they fear is a step-by-step downgrading of the hospital.

Prince Philip has already lost maternity, eye surgery and paediatric services.

But Carmarthenshire NHS Trust, which runs the hospital, said the casualty service change was temporary and it hoped to minimize the effect on patients.

We have struggled for some time to keep the department open on a day-to-day basis Carmarthenshire NHS Trust

In a statement, the trust board said they had searched "world-wide" to find the medics needed to keep the casualty department round-the-clock and the continued use of locum, or hired, doctors could not carry on.

It said: "During the last 12 months we have made every effort to fill vacant posts including a world-wide search, offering a range of financial incentives and flexible working arrangements.

"Despite our best efforts, the department's middle-grade establishment (5 posts) is currently staffed entirely by locum staff and we have struggled for some time to keep the department open on a day-to-day basis.

Overnight casualty treatment will end at Prince Philip Hospital next month

"This is regarded by our senior clinical staff to be unsafe and unsustainable.

"We are determined to provide an appropriate 24-hour service at Prince Philip Hospital as soon as possible.

"The trust is working closely with the Carmarthenshire Local Health Board, Ambulance Service, neighbouring hospitals and the Community Health Council to find safe and acceptable solutions for the future provision of A & E Services at Prince Philip Hospital."

The Commission for Health Improvement said last month that accident and emergency services were being "compromised" by a lack of staff.

Arrangements have been in place for some time for some badly injured patients to receive treatment at Morriston Hospital in Swansea or West Wales General Hospital in Carmarthen.

The trust said patients with any concerns should call NHS Direct on 0845 4647, who would advise whether they should attend an accident and emergency department.