Hywel Dda University Health Board says the number of people going to accident and emergency departments has increased at all of its hospitals this month, compared to last month.
It says some planned surgery has been postponed, so resources can be redeployed to A&E units, but it is working to ensure patients are not delayed in moving out of hospital and into more appropriate care.
Our hospitals are experiencing very high demand and a large number of very ill patients are being brought to our accident and emergency departments. Many of these patients are then being admitted to hospital for ongoing care.
We have experienced a sustained period of pressure since the start of the year and are working hard to ensure our patients receive timely and appropriate care.
The Welsh Ambulance Service says it is "very concerned at the handover delays that have been experienced recently".
It is "concerned that pressure across all hospitals in Wales has a direct impact on the ambulance response that is able to be provided to patients who call 999 for our help."
"Ambulance crews continue to provide clinical care for patients as they wait to be admitted into hospital and we provide ambulance clinicians, where possible, to care for patients in emergency departments to support the nursing and medical staff in hospitals."
The Welsh Government has urged patients to "think before attending the Emergency Department or dialling 999."
People with minor injuries or illnesses are being asked to consider other options, to reduce pressure on A&E departments:
- Self care: Keep a medical cupboard well-stocked, and rest at home
- Advice: NHS Direct Wales can help with health questions and help find local services. The helpline is 0845 46 47 and the website www.nhsdirect.wales.nhs.uk
- Community support: A pharmacist can provide expert advice, and provide medicine without an appointment
- Routine care: An appointment with your local GP when it's not an emergency
- Urgent care: If you need urgent healthcare, phone your GP surgery or out of hours service - for urgent dental care contact the NHS Direct Wales Dental Helpline on 0845 46 47
- Emergencies: Call 999 and ask for the ambulance service for serious emergencies, or go to an A&E department
The Welsh Government says there has been "a significant increase in emergency pressures during the last week."
It says some staff have been redeployed to help out in A&E departments.
To help manage the pressures, NHS Wales has held Daily Executive Conference calls. Chaired by the Welsh Ambulance Service they include all Local Health Boards and Welsh Government Officials.
The NHS has been reprioritising some of their clinical staff to help with the pressures, for example, GPs and local Primary Care teams have been actively involved in supporting hospitals by managing patients where ever possible in their communities.
Morriston Hospital Accident and Emergency Department in Swansea had its highest ever levels of attendance yesterday, with more than 300 patients presenting for care.
Abertawe Bro Morgannwg University Health Board says it has seen a high number of emergency admissions, and its A&E departments are extremely busy and under pressure.
Cardiff and Vale University Health Board has also apologised to patients for delays in treatment, particular in the emergency unit at the University Hospital of Wales.
It says there has been "exceptional demand on our services", and "in some instances we have not met the standards we set ourselves."
We would like to apologise to anyone who has experienced any delay or discomfort during their care in recent days and assure them staff are doing all they can to meet the exceptional demand on our services.
The Emergency Unit at University Hospital of Wales has been under consistent pressure.
On Monday there were more than 455 attendances, the highest this year.
Of those 42% were major cases, patients with serious injury requiring complex and expert care.
The high demand and complexity of the patients we are treating has meant that in some instances we have not met the standards we set ourselves.
Hywel Dda University Health Board has apologised for forcing patients to wait in ambulances outside Bronglais Hospital in Aberystwyth.
Mark Brandreth, Director of Planning and Operations at the health board, said: "Any patient waiting in an ambulance is assessed, managed and treated according to their needs by our doctors and nurses."
Bosses say ambulance admissions across Wales are currently 22 percent higher than predictions for this time of year.
Some planned surgery has been postponed, to provide more resources to the emergency department.
The health board is asking people with minor injuries or illnesses to try other options, such as getting advice from a local pharmacist or GP, or using minor injury units, rather than going to Bronglais.
Plans to move some maternity services from North Wales to the Wirral have already caused a series of protests.
This evening, demostrators gathered outside the offices of the Health Minister Lesley Griffiths.
Our North Wales reporter Ian Lang was at the demonstration.