Inspectors at Colchester Hospital found a patient had been given a sedative without any evidence that consent had been sought, the Care Quality Commission (CQC) has said.
The health watchdog also found that staff had not followed or reviewed notes of a patient to follow a 'do not resuscitate' notice from a previous admission.
The CQC said the inspection took place after "information of concern" had been brought to its attention.
The hospital has closed its Emergency Assessment Unit after overcrowding and says the public should only visit if they have a "serious or life-threatening condition".
The Care Quality Commission (CQC) says it will continue to monitor Colchester Hospital after raising concerns over its Accident and Emergency Assessment Unite (EAU).
Professor Mike Richards, Chief Inspector of Hospitals at the CQC, said: Following the inspection, we gave feedback to the trust about our safeguarding concerns so that it could take appropriate action to ensure the safety and wellbeing of its patients.
"We will return to carry out further inspections at the trust and we are working urgently with Monitor to resolve these issues," he added.
The CQC will publish a full report of its findings "in due course".
Colchester Hospital has declared a "major incident" over concerns raised by a surprise inspection last week.
The hospital has called on members of the public only to visit the hospital's accident and emergency department if they have a "serious or life-threatening condition".
It comes after an inspection by The Care Quality Commission on Wednesday raised "safeguarding concerns".
Peter Wilson, acting chairman of Colchester Hospital University NHS Foundation Trust, told the Guardian newspaper it was facing "unprecedented demand" on its services.
He confirmed it had declared a major incident, expected to last a week, to review various aspects of service at the hospital.
Cordons have been lifted at Southend Airport after police said the suspicious package turned out to be a bag of "rubbish".
Essex Police tweeted:
Southend Airport wrote on Twitter after it was evacuated due to a suspect package being found:
We are currently dealing with an incident. More information will follow as it becomes available.
Essex Police posted on Twitter after reports of loud bangs heard at Southend Airport:
The company behind hit reality TV show The Only Way Is Essex is ordering a local fish and chip shop to change its name 'The Only Way Is Fish'.
Production company Lime Pictures claim the branding on the shop in Ongar, Essex, is an "infringement of our copyright" and have given owner Dave Edwards 14 days to remove his signs and stop using similar logos on his Facebook page.
Dave, who only opened his business in March has accused them of an "infringement of human rights," according to a Masons News Service report.
The father-of-three said: "We are not trying to impersonate TOWIE - it's only a gimmick. If you sell good fish and chips people will come back. I don't think it is the name they have come for."
The family of one of the two men killed in a light aircraft crash in Essex yesterday have paid tribute to him, saying they love him "more than anything in the world".
Simon Chamberlain, 29, was travelling as a passenger when the Yak 52 plane downed after flying out of North Weald airfield. His family said:
Lizzie, his wife, has lost her best friend and soul mate. His son, Charlie, who will be two years old in August, has lost his father. And his parents, Paul and Steph, have lost a loving son. We love him more than anything in the world.
Our hearts also go out to the other person involved in this tragedy.
Police have said they are not in a position to identify the pilot, but confirmed yesterday that he was also from Essex.
The two victims of a light aircraft crash in Essex were confirmed dead at the scene despite the "best efforts of (ambulance) crews" to save them.
An East of England Ambulance Service spokesman said:
The ambulance service was called at 2.55pm today, dispatching an ambulance, three paramedic officers, the hazardous area response team (HART) and Magpas helimedics.
Despite the best efforts of crews the casualties were sadly pronounced dead at the scene. Ambulance resources have now been stood down.