A motion calling on the Government to release unpublished technical archaeological reports concerning burials at the former Bessborough mother and baby institution was passed unanimously on Monday.

The motion at Cork City Council also called for the release of burial records related to the institution, held within the archive of the Commission of Investigation into Mother and Baby Homes, and for the Government to direct the Attorney General to open an inquest into deaths at the institution “as a matter of moral urgency”.

The motion, proposed by Labour councillor Peter Horgan, received cross-party support at a meeting on Monday evening.

It is the latest effort in a campaign to overturn a controversial decision to grant planning permission for more than 100 apartments at the site of the former institution.

Speaking to The Irish Times after the meeting, Horgan said the fact the motion received unanimous support showed the issue was not a “political football”.

“Across all parties and non-parties there was no dissenting voice tonight … that’s something that shouldn’t be dismissed, and I would hope that the Government hears that,” he said.

More than 900 children died at Bessborough or in hospital after being transferred from the institution, which operated from 1922 to 1998.

Despite “very extensive inquiries and searches”, the commission of investigation was able only to establish the burial places of 64 children, meaning the burial places of more than 800 children remain unknown.

The inquiry concluded it was likely some of them were buried in unmarked graves but did not consider it feasible to excavate the full site, which amounts to 24 hectares. The entire estate covers about 80 hectares, parts of which have already been built on.

Horgan described Bessborough as “a spectre that haunts the community” and said he proposed the motion in a bid to “uncover the truth”.

“A lot of people say there’s nothing there. Well, if there’s nothing there – and you did the investigation, release the results … If there’s something there, release the results.”

Horgan said he hoped the Government would act on the motion. “If they don’t, then we’ll have to keep banging this drum.”

The council will write to the Taoiseach, Tánaiste, Minister for Children and the Attorney General about the matter this week. The Department of Children has been approached for comment.

In February, developer Estuary View Enterprises was granted planning permission by the council to build 140 apartments at the site. Horgan and the Bessborough Mother and Baby Home Support Group lodged appeals with An Coimisiún Pleanála (ACP), which in July upheld permission for 106 apartments.

In its ruling, ACP said there was no evidence of unrecorded burials in the area where the development was proposed. Conditions attached to the permission include forensic archaeological monitoring during construction works and the appointment of a liaison officer to engage with survivor groups.

“Should human remains be discovered, full forensic controls would be applied. This includes stopping works, securing the area and notifying the Cork city coroner immediately,” the decision noted.

Campaigners aiming to overturn the decision last month lodged judicial review proceedings in the High Court.

Opposition parties have called on the Government to buy the site via a compulsory purchase order.

Taoiseach Michéal Martin in July said he had “asked Cork City Council to engage with the landowners at Bessborough with a view to exploring all options for the future of the site”.

“Bessborough is of huge importance to many people and families, at home and abroad. We need to do the right thing for all concerned,” he said in a statement.