Calling for Ofsted to be abolished could risk “squandering” a real opportunity for change, the sister of Ruth Perry has said.

Professor Julia Waters has called on unions to focus on “working constructively” with the inspectorate following the death of her sister.

Her comments came after delegates at the annual conference of the National Education Union (NEU) voted for a “public facing” campaign calling for Ofsted to be abolished to be launched by the union.

The motion, which was passed at the union’s conference in Bournemouth on Wednesday, also called on the NEU to advise its members to “refuse to work” as Ofsted inspectors until “full reform has been implemented”.

It comes after Ofsted has come under greater scrutiny after the suicide of headteacher Ruth Perry.

Mrs Perry took her own life after an Ofsted report downgraded her Caversham Primary School in Reading, Berkshire, from its highest rating to its lowest over safeguarding concerns.

But Prof Waters, who is due to address the NEU’s conference on Friday morning, said: “I agree wholeheartedly with everything the NEU is trying to do to improve school inspection, right up to the point when they call for Ofsted to be abolished.

“Yes, the system needs fundamental reform. Teachers and headteachers are still facing intolerable pressure from inspections. This cannot be helpful to children or parents.

“But, while understanding the strength of feeling, I do not believe that calling for Ofsted to be scrapped helps anyone.

“The current government won’t do it, a future Labour government wouldn’t do it. So why waste the energy and risk squandering the current opportunity for change?”

She added: “Part of the reason why Ofsted seems to have refused to listen to teachers and unions in the past is because its leadership has shown itself to be dangerously resistant to valid criticism.

“It has proven all too easy for Ofsted to refuse to listen to an organisation that says it shouldn’t exist. We simply can’t afford that anymore.

“In the interests of teachers, headteachers, children and parents alike, I urge the teaching unions to focus on working constructively for a more supportive, more reliable, kinder, safer inspection system.”

Last month, Sir Martyn Oliver, chief inspector of Ofsted, launched the watchdog’s Big Listen public consultation that will seek views about Ofsted.

In his first major speech since becoming chief inspector in January, Sir Martyn said he wanted to “mark a new chapter” with the sector, adding that “nothing is off the table”.

The motion, which was passed on Wednesday and mentioned Mrs Perry, called on the NEU executive to encourage “the removal of all mention of Ofsted judgements in publicity material”.

It also called on the union to support members in “balloting for, and taking, strike action” when “mocksteds”, deep-dives and excessive workload have arisen through Ofsted pressures.

Findings from a survey of NEU teacher members in England, released at the conference, suggested that 82% believe a new system of inspection should be introduced because Ofsted has “so many problems”.

During the debate, delegate Ian Walters, from Derby, described Ofsted as a “ruinous regime” and he said he had witnessed a number of “rude and intimidating inspectors” over the past 20 years in the profession.

Addressing the conference, he said: “Ask yourself how many of your colleagues have been seriously impacted by Ofsted? How many have left the profession? In many cases losing talented, dedicated professionals as a result of their experiences at the hands of this menace to education.”

He added: “I walk into school every morning past a banner proudly claiming to be rated Good or Outstanding by Ofsted. This makes me embarrassed and ashamed of what my profession has become.

“By placing banners like this at the school gates and on publicity materials, we are normalising this vicious broken system and accepting that it has legitimacy.”

Daniel Kebede, general secretary of the NEU, said: “NEU members have made their feelings very clear: Ofsted causes more harm than good and we need urgent and fundamental reform.

“The profession can be trusted to do their jobs effectively without a punitive, high-stakes system to keep them in line.”

He added: “Whilst the NEU continues to campaign on a national level for a new system which is supportive, effective and fair, it is vital that our members are protected from the harmful impact of Ofsted on the ground.

“Our new Ofsted risk assessment form offers members a means of organising their workplace to ensure the health and wellbeing of members is both prioritised and protected – before, during and after an inspection.

“In the meantime, we urge NEU members to cease work as Ofsted inspectors and not to display their school’s judgements on banners and other publicity materials.”

A Department for Education (DfE) spokesperson said: “Our plan to ensure every child benefits from a world-class education is working with 90% of schools now judged to be Good or Outstanding, up from 68% in 2010.

“Ofsted is central to driving forward that improvement. Their independent inspections are vital to ensuring children are safe in school, parents are informed, and the Department is able to intervene where strictly necessary.

“We have worked closely with Ofsted to ensure inspections are conducted with professionalism and compassion. We are supporting Sir Martyn Oliver’s work through the Big Listen, to hear from parents, teachers and education experts to understand where more improvements can be made.”