The length of GP consultations in the NHS is "crazy" and risks undermining care if more patients are pushed out of hospitals, doctor leaders are warning.
Average consultation length is 10 minutes in the UK - thought to be the shortest in the developed world.
GP leaders said this was already too short and the extra workload from the hospital closures proposed by local leaders would destabilise care.
The proposals are being made by local health leaders to "modernise" the NHS.
There are 44 plans in England - many of which involve reducing hospital care and pushing more services into the community to save money and make the NHS more efficient. Similar measures are being taken in the rest of the UK.
Meanwhile, polling by Ipsos Mori for the BBC of 1,033 UK adults has suggested the public would be open to a tougher approach on people who abuse the GP system.
Seven in 10 said charging people for missed appointments would be acceptable.
A majority - 51% - said they were against paying to have a guaranteed appointment within 24 hours, although 20% said they would be willing to pay more than £10.
NHS Health Check
A week of coverage by BBC News examining the state of the NHS across the UK as it comes under intense pressure during its busiest time of the year.
Both the Royal College of GPs and the British Medical Association are against the idea of charging.
Instead, they said, the attention should be given to the impact of the local plans.
The RCGP and BMA said they would result in even more complex cases being passed on to GPs once they start being introduced later this year.
The number of consultations carried out has already risen by nearly a quarter in the past five years, and GPs argue the ageing population means growing numbers of patients have complex conditions that cannot be dealt with in the normal 10-minute consultation.
Research by the Health Foundation - based on information provided by GPs from 11 countries, including Germany, France, Australia and the US - has suggested the amount of time spent by UK GPs with patients is the lowest in the developed world.
The data showed 92% of consultations in the UK are completed in under 15 minutes, compared with 27% in other countries.
RCGP president Dr Helen Stokes-Lampard said: "We have the shortest consultations in Europe. It is a crazy situation.
"They want to push more care out of hospitals, but we do not have the resources or infrastructure in the community to cope."
She acknowledged funding was increasing - by 2020 the amount spent on GPs will increase by 14% - but said this would not be fully in the system by the time the local plans were introduced.
"We will need to provide more complex care," said Dr Stokes-Lampard. "That takes time - longer than the 10 minutes we get now. I really worry what will happen.
"The typical patient has a range of multiple conditions. They can have diabetes and heart disease and some moderate depression. Patients can be on 10 medicines. You can't possibly provide good care in 10 minutes to these sort of patients.
"If we had longer, you could do so much more to reduce hospital admissions and repeat attendances."
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Dr Chaand Nagpaul, of the BMA, said he agreed.
"We spend less than other European countries. We have fewer doctors than other European nations," he said.
"We have one third of the hospital beds per head compared to Germany for example, GPs spend less time per patient than any other European nations.
"We need to be addressing these issues as a priority."
Life on the front line
Dr Olivia Hum has been a GP since 2007. She works in a surgery in Lewes, east Sussex.
"The intensity of the work in 2017 is really bad. We work 10 to 12 hours a day without a break," she says.
She says the pressures are compounded by crowded A&Es and long hospital waiting lists for operations, which means GPs are dealing with deteriorating symptoms as people wait for their treatment.
"GPs are burning out, they are overworked and many are retiring early. The system is unsustainable now.
"It is not safe - the brain can't make these decisions properly in less than 10 minutes. Quality of care and patient safety is compromised."
A Department of Health spokeswoman said the GP investment programme in England would make a real difference to doctors.
She said it would "help cut red tape, pay some of GPs' high insurance costs, and deliver innovative new schemes to retain more GPs".
The government is aiming to increase the GP workforce by 5,000 by 2020 - a rise of 16%. Meanwhile, on Tuesday ministers announced the push to recoup more money from foreign patients not entitled to free care would be extended to GPs.
Under changes to their contract they will be expected to check if patients are entitled to free care during registration. On Monday they said hospital would also be expected to ask for ID.
The governments in Scotland and Wales also said they were investing in general practice to give doctors more time to spend with patients.