"Emergency departments are in a really difficult and in some cases a complete state of crisis right now ... and in many cases we are unable to provide care at the standard we would like," Ian Higginson, vice-president of the Royal College of Emergency Medicine (RCEM), told BBC radio.
About the pressure on the health system Higginson said there are patients who even wait up to four days for emergency care.
"This is a real problem, it's happening now in our emergency departments, and we need to acknowledge it," he added.
Earlier, the RCEM said it believes this will have been the worst December for hospital bed occupancy and emergency care delays.
"There's no doubt that if you can't get an ambulance to someone who's having a heart attack or a stroke, that some of those patients are going to come to harm and may die as a result of that," said Higginson.
Meanwhile, Adrian Boyle, the RCEM president, said on Sunday that there are deaths of an estimated 300 to 500 people each week as a result of delays to emergency care, BBC reported.
Pressure on the health system is rising across UK due to the strikes and increase in flu cases. Additionally various hospitals have declared critical incidents recently.