A plan by Barnet Council to sell a library, arts centre and car parks is set to go ahead despite fears it will hand too much power to a developer.

The Labour opposition group’s bid to force a rethink of the sale of council-owned sites in North Finchley to developer Regal failed as Conservative councillors voted the agreement through during a full council meeting on Tuesday.

Under the planned regeneration of the town centre, sites including North Finchley Library, Arts Depot, and Lodge Lane and Woodhouse Road car parks, will be sold to developer Regal to help provide new homes and community infrastructure.

Labour referred the decision from the housing and growth committee to full council, warning the town hall and local community could lose out because it would “shift the balance of power from the council to the developer”. The Conservatives accused Labour of holding up plans that would improve the town centre.

Speaking during the full council meeting, Labour’s Ross Houston said: “The developer is not just being handed a black cheque – [it is] a blank cheque they can cash in at any time.”

Cllr Houston told the meeting Labour wanted to see plans that were co-designed, fit-for purpose, and would deliver long-term value for the council and benefits for the community – but said none of these had been secured in this case.

He also pointed out that a partnership board to involve residents and businesses had not yet been set up and added that the council would get overage only after developer profit. Cllr Houston also questioned whether 50% of the homes would be affordable and why the council had not considered a partnership approach that would see it retain ownership of the sites and develop planning applications alongside Regal.

Cllr Houston said: “Any development must be sympathetic and involve the real involvement of those who live and work there. But the Conservatives who run this council do not stand up to developers, and we have no confidence they will get this right.”

Gabriel Rozenberg, leader of the Liberal Democrat group, backed Cllr Houston’s comments. He said the contracts with the developer needed to be signed – but only when the residents “are fully informed and on board, and are taking part in this process”.

But Richard Cornelius, Conservative chair of the housing and growth committee, defended the plans. He said: “We all agreed that North Finchley needs some TLC [tender loving care] and the borough and London need housing, the bus station needs sorting, the library needs to be reprovided, and this we saw as an opportunity to move forward and really get something good going.”

Cllr Cornelius also claimed Labour’s referral of the agreement to full council was “an attempt to be damaging” and would hold up a consultation with residents.

Council leader Dan Thomas said: “Cllr Houston talks about blank cheques. There is no blank cheque. Taxpayer assets will only be put into the scheme if we get best consideration and […] subject to planning consent.”

Cllr Thomas accused Labour of a U-turn on the North Finchley regeneration and of trying to “politicise” the issue, claiming the current agreement was focused on switching to a new developer after the previous one pulled out. He said the partnership board could only be set up after a developer was “on board”.

The leader said: “The people and traders of North Finchley drastically want change. You have delayed it. We are getting the job done.”

At the end of the debate, Labour and the Liberal Democrats voted against the North Finchley site assembly and land agreement. However, the agreement was approved after members of the Conservative administration voted in favour.