Thousands of people's personal details – including medical records of people in the Sudury area – have been lost after a hospital laptop was stolen from a car.
The laptop, belonging to Colchester General Hospital, contained "several thousand" names of patients – including many in South Suffolk and north Essex.
It was stolen from the car of a senior manager while it was parked in Scotland, on June 18.
It took the hospital – which has just gained NHS Foundation Trust status – two weeks to tell those affected.
A letter sent to thousands of people on Monday informed them their name, date-of-birth, postcode, hospital number and details of medical treatments had been stolen.
The letter from Peter Murphy, chief executive of the hospital trust, said: "The computer contained personal information on several thousand of our patients, among many other files of less sensitive data."
He said data on the laptop was not encrypted and "there was a very small chance the patient details can be accessed".
He added: "The trust offers all affected patients its sincere apologies for putting their confidential information at risk.
"Patients and the public should be reassured that the trust takes security and patient confidentiality very seriously.
"We are holding an investigation into how this incident occurred and its consequences and have suspended the member of staff involved until the investigation concludes."
- Have your details been lost in the breach of security at Colchester Hospital? Contact the Free Press with your view.