Public bodies have already spent close to £10m on lawyers for the Grenfell Tower inquiry, and the final bill is expected to be many times higher when all the initial costs are added up.

The first legal bills, which were disclosed in response to freedom of information requests by the Guardian, represent only a fraction of what could become one of the most expensive public inquiries in British history.

A large number of lawyers, including 32 QCs, several of whom can charge £220 an hour, are dissecting the causes of the biggest single loss of life in London since the second world war.

The costs to the taxpayer disclosed so far are equivalent to the amount spent on refurbishing the tower, a project that contributed to the June 2017 fire which claimed 72 lives.

The bill is likely to rise significantly higher when fees for seven QCs, 11 barristers and 20 firms of solicitors who represented the bereaved, survivors and residents are published later this spring alongside the conclusions of the inquiry chairman, Sir Martin Moore-Bick, about what happened on the night of the fire.

The legal costs for representing the families of the 96 people who died at Hillsborough before and during the two-year inquest which ended in 2016 eventually reached £63.6m.

According to disclosures, the Home Office, which is responsible for fire and rescue policy in England, has already spent £2.1m on lawyers, while the Royal Borough of Kensington and Chelsea is expected to have spent £5.8m by April.

The London Fire Brigade has spent £600,000, including more than £250,000 for its lead counsel, Stephen Walsh QC, and his junior, Sarah Le Fevre. The mayor of London, Sadiq Khan, spent £98,000 instructing counsel and the Ministry of Housing, Communities and Local Government has spent £600,000, including nearly £240,000 on barristers.

The Metropolitan police and the Kensington and Chelsea Tenants Management Organisation are yet to respond to requests for information, but their spending is likely to push the figure for public bodies’ spending beyond £10m.

Legal costs for the first nine months of the inquiry and the cost of renting rooms at the Holborn Bars conference complex will be published when Moore-Bick delivers his findings from phase one of the inquiry.

Hearings into how the building was refurbished are unlikely to start before the end of the year, and lawyers have started to comb through 200,000 documents that are expected to be disclosed.

Advocates for fair inquests and inquiries stressed it was right that there was “equality of arms” between the 568 people – mostly the bereaved, survivors and residents (BSRs) – who have been granted core participant status, the 10 public bodies and the 20 commercial organisations involved in the refurbishment.

Deborah Coles, the director of the Inquest charity, said: “Any concern about cost to the public purse should not fall on the families’ side. The BSRs need to be represented to have their voices heard. You can’t compromise on families’ access to a process that is about finding the truth about what happened.”

The inquiry is preparing to move into new premises in west London before the second-phase hearings begin, partly to make room for more lawyers, whose numbers are expected to be swollen by the legal teams of the private companies involved in the refurbishment.

Twenty companies, including the contractor Rydon, the cladding manufacturer Arconic and the architect Studio E, have already appointed 17 QCs, four barristers, one solicitor advocate and 20 firms of solicitors. Their costs are likely to be met by the companies themselves or their insurers.

The inquiry’s own legal team – four QCs, 22 junior counsel, 10 solicitors and a team of junior barristers and paralegals assembled to review hundreds of thousands of documents – will further increase the cost to the taxpayer.

To limit rising costs, Moore-Bick has told interested parties to share lawyers where possible and has said costs will not be met for “substantial bodies” or people, such as employees, whose costs could reasonably be expected to be met by such bodies.

The cost of the 10-year Savile inquiry into Bloody Sunday in Northern Ireland reached £195m.