Campaigners have accused Manchester city council of a PR own goal after a £1m memorial to the Peterloo massacre was quietly made public three days before the 200th anniversary.

The monument, designed by the Turner prize-winning artist Jeremy Deller, prompted criticism earlier this year when disability rights groups pointed out it would be inaccessible to wheelchair users.

It was expected that a new version of the memorial would be formally unveiled on Friday during a public event to mark 200 years since the bloody protest for parliamentary reform.

Manchester: Jeremy Deller unveils design for Peterloo memorial Read more

However, there was no fanfare or ribbon-cutting when the sculpture was made public for the first time on Tuesday, as a team of construction workers took down the metal hoardings before a deserted square in Manchester city centre.

Mark Todd, a Manchester-based accessibility advisor who previously worked on the London 2012 Olympics, said: “We asked the council at every turn: ‘Are you planning to have an unveiling?’ Because that is something we would have a problem with, because we consider it unfinished until it’s made accessible.

“I don’t know but I suspect our campaign has had the effect of making them not want to make a big song and dance about it because it should be accessible as a speaking platform.”

Todd added: “As it’s currently designed, everybody is stood at the top speaking down to disabled people at the bottom. If you wanted the worst metaphor for inequality, there it is.”

The monument is made up of 11 concentric steps featuring the names of the 18 people who died in the Peterloo massacre and the towns from which they travelled. The idea behind the design was that people would walk to the top of the monument as a speakers’ podium.

Other campaigners said it was a “kick in the teeth” for such an important monument to be so inconspicuously made public, contrasting it to the crowd of thousands who welcomed the unveiling of an Emmeline Pankhurst statue in December.

Denise Southworth, a direct descendant of Mary Heys, one of the 18 peaceful protestors who died at Peterloo, said: “They will have all these dinners – 20 years since Manchester United won the treble – but for something like this they don’t want to know. It’s nothing short of disgraceful.”

Paul Fitzgerald, chair of the Peterloo memorial campaign, said the council had been left in “this embarrassing, awkward and weird situation” by failing to properly consult people on the design of the monument until it was too late.

He said: “The fact that there’s this strange embarrassment and nobody really wants to go anywhere near the memorial is a testament to their lack of democratic participation. I cannot think of a single excuse for them leaving the announcement of the design until so late that it couldn’t be changed and that’s a mockery of the democratic process and we’re extremely angry with them about it.”

Cllr Luthfur Rahman, the executive member for culture for Manchester city council, said: “In keeping with the spirit of Peterloo, the focus for the anniversary is on grassroots voices and not the civic ceremonial of a grand unveiling. The council has acknowledged that the innovative and imaginative interpretation of the design brief, with a greater emphasis on interaction than originally envisaged for a public artwork, meant that not enough consideration was initially given to accessible design issues.

“But we have listened to – and engaged with – the concerns of disability access campaigners who have raised this issue, and we are committed to making modifications to ensure the monument is fully accessible, so that everyone can reach the top. Both the council and Jeremy Deller are determined that the solution will be of the highest design quality and make a positive contribution to the overall appearance of the memorial as well as its accessibility.”

Todd said he was meeting Deller and council officials later this week to discuss ways to make the monument fully accessible. He said: “It’s a difficult task. It’s not easy to make accessible something this inaccessible. It is an own goal but they’re trying to get two goals back in the last minute to make it a better result.”