One in 10 GPs believe their patients may have died as a result of poor hospital care, according to a survey that paints a "bleak picture" of care around the country.
More than a third said they know patients who have received "dangerously sub-standard" care at their local hospital in the last year, according to data collected from 500 family doctors by GP magazine Pulse.
GPs said complaints ranged from patients being discharged too early, receiving poor A&E care or dying due to a missed diagnosis.
The head of the Patients Association said the figures painted a "bleak picture" of health services around the country.
"The response to this survey are things we hear about all of the time via our Helpline," Katherine Murphy, told The Huffington Post UK.
"Patients being discharged when they are not medically fit to be, incidences of misdiagnosis, poor communication and a failure to act speedily and efficiently."
A GP in Oxford who wished to remain anonymous said he believed the John Radcliffe Hospital had missed three "serious" diagnoses in the gynaecological department, including one of ovarian cancer.
"I think the patient with cancer has died," he told Pulse.
"We wrote a letter. All we wanted was something back saying 'let’s look at this'. Instead we got a five-sentence reply saying 'under Nice guidelines we did nothing negligent'."
Dr Peter Livingstone, a GP in Glasgow, told Pulse he had raised concerns over "dangerous" premature discharge.
"A patient had been admitted on Saturday and discharged on Sunday.
"A chest X-ray had found left broncho-pneumonia. When I saw him he was unresponsive, his pulse was running too fast, he had a fever and his blood pressure was down.
"They turfed him out thinking a nursing home would look after him. That is sub-standard care - I worry he may have died."
A fifth of GPs surveyed said they would not recommend their local hospital to a family member and one in five said they had warned patients about receiving care at a local provider. And some 15% said they knew departments in their local hospital where they believed care was "dangerously below standard."
However the poll also revealed that 64% of GPs rated hospitals’ clinical care as "good" or "very good".
Samantha White, whose mother died in Glenfield hospital in November 2010 told The Huffington Post UK staff has displayed a "total lack of care". "I was up to the nurses desk they were totally dismissive, they didn't want to know because they didn't know what to do. There was no one there authorised to increase her pain medication, it was so horrendous. "
Richard Hoey, editor of Pulse, said the figures showed only a "significant minority" raised concerns about levels of care similar to those in the Mid Staffs hospital scandal (http://www.dailymail.co.uk/news/article-1253438/Mid-Staffordshire-NHS-hospital-routinely-neglected-patients.html), as well as "plain dangerous" A&E departments.
"The results shouldn’t detract from the very good quality of care in most NHS hospitals, but they suggest the minority which are bad and unsafe is larger than the government might like to admit."
Dr Clare Gerada, the chair of the Royal College of General Practitioners said the concerns raised by GPs should be heeded.
"Locally the GPs need to have conversations with their hospital managers or consultants to try and sort this out.
"But what I wouldn't like to see is us having a divide between GPs and hospital doctors - this is what happened under fundholding and it divides us to the detriment of patients."
In a statement the Department of Health said: "Unsafe care will not be tolerated. We are developing patient safety measures which will show the outcomes of care."