Embattled staff at St Bartholomew's and the Royal London Hospital will be given powers to turn away violent or abusive patients under a new charter to be introduced next month.
Patients or visitors breaching an 'agreement of care' could be asked to leave the premises or be referred to 'another unit' if they are still in need of treatment.
The agreement, thought to be a first by the trust and patients' groups, was drawn up by lawyers Beachcroft Stanleys.
It is designed to protect staff and members of the public from harassment or bullying under the terms of the 1997 Protection from Harassment Act. Under the act, offenders can face a 5,000 fine or a five-year prison sentence.
The agreement applies to violence and abusive, sexist or racist remarks, as well as drinking or drug-taking on trust premises. Copies of the contract will be held on medical records for three years.
'It is a tiny minority who disrupt services for others,' said a trust spokesperson. 'But they have to know that they have certain rights and responsibilities.'
Elaine Cole, a sister at the Royal London Hospital's accident and emergency department, said a young male nurse recently suffered a broken nose when he was head-butted by a man who had come in complaining of back pain.
'That patient still comes in and still expects to be treated like a human being,' she said.
'This contract is an indication to those who need it of the standards of behaviour expected of them.'
Health secretary Frank Dobson is expected to use the platform of the Labour Party conference in October to launch a consultation document on a revised Patient's Charter.
This is expected to set out patients' duties as well as rights.
Dawn Webster, chief officer of Tower Hamlets community health council, said the contract was a good idea, although she argued that patients needed assurance they would be treated if they were in need.
'Having a policy in place and being able to wave a piece of paper around might not protect a nurse,' she added. 'There has to be some training to go with this.'