More than a quarter of NHS workers have been bullied, harassed or abused in the last year, while four in 10 have felt unwell due to work-related stress, a poll suggests.

The national NHS staff survey for England, which included responses from 569,440 staff, found 29% have experienced at least one incident of bullying, harassment or abuse in the last 12 months from patients, their relatives or other members of the public.

The figures include around one in seven (15%) who have been physically attacked, up slightly on the year before.

Rules have now been tightened so that hospitals can refuse, in non-emergency cases, to treat patients or visitors who are aggressive, abusive or discriminatory, such as those who attack somebody's ethnicity or sexuality.

The poll found that staff at ambulance trusts and mental health or learning disability trusts were worst affected by abuse and violence, although 19% of all NHS staff have also been harassed, bullied or abused by colleagues, and 12% by managers.

Among NHS staff who have frequent face-to-face contact with patients or service users, 37% have experienced bullying, harassment or abuse from patients, their relatives or other members of the public.

Other findings from the 2019 poll showed that 40.3% of staff reported feeling unwell as a result of work-related stress in the previous 12 months, up from 39.8% the year before and 36.8% in 2016.

Some 22.9% also said they had unrealistic time pressures, up from 20% the year before.

Meanwhile, there has been a drop in the proportion of staff working extra unpaid hours in the past five years, although 55.9% still do so every week.

But more staff in 2019 reported being happy with the quality of care they can provide and more than before said they would recommend their place of work to friends and family for treatment.

Health Secretary Matt Hancock has now written to all NHS staff, telling them "being assaulted or abused is not part of the job".

The letter said: "There is far too much violence against NHS staff, and too much acceptance that it's part of the job. Far too often I hear stories that the people you are trying to help lash out.

"I've seen it for myself in A&Es, on night shifts, and on ambulances. I am horrified that any member of the public would abuse or physically assault a member of our NHS staff but it happens too often."

Mr Hancock said the NHS has joined forces with the police and the Crown Prosecution Service to approve a Joint Agreement on Offences Against Emergency Workers.

He added: "This will ensure that those who act violently and with criminal intent towards NHS staff are swiftly brought to justice.

"The joint agreement provides a framework to ensure effective investigation and prosecution of cases where staff are the victim of a crime and sets out the standards victims of these crimes can expect.

"All assault and hate crimes against NHS staff must be investigated with care, compassion, diligence and commitment.

"I ask that you please ensure that you report every incident and act of abuse or violence against you or a colleague. No act of violence or abuse is minor."

Sir Simon Stevens, NHS chief executive, said: "We are determined to clamp down on abuse and aggression in all its forms."

Unison assistant general secretary Christina McAnea said: "Matt Hancock's tough talk is welcome, but it comes many months after he promised to tackle violence. These figures show there's been no noticeable change."

A separate survey due to be published by the Parliamentary and Health Service Ombudsman on Wednesday found that one in five mental health patients do not feel safe in NHS care.

More than half of people with mental health problems in England also said they experienced delays to their treatment, while four in 10 (42%) said they waited too long to be diagnosed.