The trust which runs Princess Royal Hospital is urging people to stay away from A&E unless they need emergency treatment.
Brighton and Sussex University Hospitals Trust have posted the message on the home page of its website.
The statement reads: “We are currently under severe pressure - please don’t come to A&E unless you are in need of emergency treatment.
“Non-emergency patients are likely to have an extremely long wait and will be taking staff away from caring for patients who need emergency or life-saving care.
“Because of this severe pressure some appointments are being cancelled but we will call the patients affected directly. If you haven’t heard from us, please attend your appointment as normal.
“Please bear with us during this time of unprecedented demand and help us to prioritise patients who are in most urgent need.”
The number of people calling 999 during January 3 and 4 is up by close to 30 per cent on the equivalent weekend in 2014.
Sue Braysher, Chief Officer for NHS Horsham and Mid Sussex CCG and Chief Operating Officer for NHS Crawley CCG, said: “A&E and 999 are for emergencies - if it’s not an emergency, other services are available, 24 hours a day, 7 days a week. We know that 1 in 3 visits to A&E could be dealt with outside of hospital. People often think that visiting their local A&E or calling 999 is their only option when their GP surgery is closed, but this is not the case. There are lots of services that offer treatment and advice in the evenings and at the weekend, including local pharmacists (who are trained to help deal with minor ailments), walk in centres, NHS 111 and out-of-hours GP services.”
Have you been waiting in A&E?
Alternatively you can call 01444 419583 to speak to a reporter.
To visit Brighton and Sussex University Hospitals Trust click here