Nottinghamshire County Council is likely to move out of "at least some if not all" of its West Bridgford headquarters in future, the council's leader says.

The Conservative-led authority is planning behind the scenes to work out the next stages for County Hall.

Purpose-built beside the River Trent in the 1930s, the council says the site would cost about £50m over the next decade to bring up to modern standards.

The current condition of the site – including its age and problems with asbestos – mean it would continue to cost millions to maintain.

Tory leaders have previously suggested the authority could relocate some or all services – including the council's debating chamber – to the new flagship £15.7m Top Wighay site near Hucknall.

Opposition councillors say the plans are the "worst-kept secret" in Nottinghamshire and fear the council is "selling off" precious public space.

But the Conservative administration says remaining in the West Bridgford site "isn't realistic" because of its soaring maintenance costs.

Councillor Keith Girling (Con), cabinet member for asset management, is responsible for deciding the future direction of the building.

Speaking in January, he said a Top Wighay relocation could put the council "in the heart" of the county.

Now Cllr Ben Bradley (Con), the council's leader, says a final decision on what happens next with the site will be taken by Cllr Girling in the coming weeks.

The Mansfield MP told the Local Democracy Reporting Service: "We've been doing some mapping and some options work behind the scenes to lay out what's possible.

"We've always said the cost of this building isn't realistic so from an administration point of view, we imagine we will end up vacating at least some – if not all – of it.

"Cllr Girling's decision will be about what we do with it and we don't know the answer to that yet."

Both politicians have been outspoken in the past about the commercial prospects County Hall could offer, including bars, restaurants, luxury flats or a hotel.

On January 17, Cllr Girling said: "If we've got luxury flats above and a good area below, with bars and restaurants looking out on the river, it would really lift this place and regenerate it.

"We are building Top Wighay and why wouldn't we look at being in that new building? To me, it makes complete sense."

Cllr Bradley added in December: "You can imagine, in the future, sitting out on the river with a bar and a restaurant. It would be beautiful.

"It's all speculation, but there are huge opportunities with this building and something will have to change – we can't afford to maintain all of it."

Cllr Girling will be presented with delegated decision documents from council officers in the coming weeks.

The cabinet member previously said he wanted a decision on the building to be taken by the end of March.

However, the plan may also be debated by a future full council meeting given the wider implications on the authority's estates.

But opposition parties are not convinced by the plans.

Cllr Kate Foale, the Labour Group leader, said: "Conservative county councillors are looking to sell off Nottinghamshire residents' historic public buildings and local spaces.

"[This is] in order to bail out a Government which has plunged public services into crisis by trying to deliver on the cheap."

Cllr Francis Purdue Horan, of the Independent Alliance, added: "The fact the Conservatives want to sell County Hall is Nottinghamshire's worst kept secret.

"We've always felt the real reason they are building the new £15.7million office block at Top Wighay near Hucknall is that they are considering selling County Hall to the highest bidder."