Relatives of the 22 victims of the Manchester Arena terrorist attack who are applying for legal aid for representation at the forthcoming inquest are being made to fill in a 17-page questionnaire and declare whether they have any “valuable possessions” worth more than £500 that could be sold to help cover costs.

Campaign groups have attacked the legal aid application process – which may still end in claims being rejected – as “cruel and intrusive”. They back calls for families whose loved ones are killed in terrorist attacks to automatically receive legal aid for inquests rather than be forced through the means-testing process.

“The funding process is intrusive and protracted and adds further trauma,” said Deborah Coles, director of the Inquest charity, which supports bereaved families. “The Ministry of Justice perpetuates the myth that inquests are informal and families can represent themselves. This is dishonest and fails to confront the reality of the uneven playing field that confronts families at complex inquests.”

The police, emergency and security services will receive taxpayer-funded representation when the inquest into the Manchester bombing of May 2017 starts next April. But insufficient legal representation for the victims’ families has prompted concerns that key questions may go unanswered.

“Families face multiple state lawyers, paid for at public expense, who frequently put defence of their interests above the search for the truth,” Coles said. “The past few years have seen an unprecedented focus on how agencies investigate contentious deaths and there have been repeated calls for reform so families have automatic access to legal aid for inquests. This inequality … is the single greatest obstacle to bereaved families.”

Families of the eight victims killed in the 2017 London Bridge attack learned last month – just as the inquest was wrapping up – that they will not receive legal aid. However, it emerged that the widow of the attack’s ringleader, Khuram Butt, was entitled to public funding.

Among the questions the Manchester Arena families will have to answer when applying for legal aid is whether they own a car or a timeshare, and whether they have children or a partner in employment. Further detailed guidance issued with the application reveals that articles of value must also be considered.

“Examples might be where the individual collects antiques or owns a valuable painting. Items of jewellery are included, save for engagement, wedding or eternity rings, which are disregarded. The individual is asked to declare the value of such items in their application and may be required to provide evidence of value.”

The 22 victims of the Manchester Arena terror attack. Photograph: GMP/PA

James Hodder, the partner of Kirsty Boden, a nurse who was killed in the London Bridge attack while aiding others, has launched a petition calling for bereaved families of terrorist attacks to be entitled to legal aid. It has gathered more than 250,000 signatures.

He described filling in the legal aid application form as horrendous. “I had to provide evidence that me and Kirsty were a couple as we were not married. When you are vulnerable and grieving, that’s the last thing you want to do.”

It was not until the last week of the inquest that Hodder learned his application for legal aid had been rejected. Fortunately, a law firm provided pro-bono representation.

“The official reason they give is that an inquest is not adversarial in nature so there is no need for legal representation, but that doesn’t make any sense as they gave legal aid to the perpetrator’s family. And there are adversarial elements: witnesses are cross-examined in great detail, there are complex arguments made. Weeks of CCTV footage and tens of thousands of pages of documents had to be studied by my legal team.”

In May, a letter from the justice committee to David Gauke, who was then justice secretary, said it was “fundamentally unfair for public bodies to have legal representation at the highest level of expertise while bereaved families are unrepresented”.

Coles said: “The treatment of terrorist victims is cruel and inhumane and is symptomatic of the dysfunctional and unfair process for funding family representation at inquests.”

Figures obtained from the Ministry of Justice via a freedom of information request show that, in 2017, the department spent £4.2m representing prison officers at inquests, while bereaved families received only £92,000 in legal aid. A ministry spokesman said: “We understand how distressing the inquest process will be for relatives of those who died in the Manchester Arena bombing, and we’re making changes to ensure there is more legal support … Aid has always been means-tested and rightly counts not just a person’s income or savings but expensive assets like sports cars, antiques and jewellery. It is possible for the Legal Aid Agency to waive the means test if appropriate.