A Surrey hospital is warning people not to attend accident and emergency unless they really need to because of "unprecedented" numbers of patients.
St Peter's Hospital at Chertsey said there had been several days of intensive activity at A&E which was causing long waits.
A spokeswoman said there was no specific reason for the high demand.
"We would like to ask the public to think twice about whether a visit to A&E is really necessary," she said.
"The A&E department should only be used when people have suffered trauma, had an accident or have developed a serious illness and are unable to receive advice from their local pharmacist, GP or walk-in centre."
The spokeswoman said there were high numbers of both ambulance and walk-in patients which had combined to make A&E very busy, despite normal staffing levels.
"This happens from time to time," she said. "Sometimes people come to A&E when they don't really need to.
"There have been no knock-on effects elsewhere in the hospital, although it is very busy, but we don't want to get to a point where we have problems."