A major development on one of Kent’s busiest high streets has been put up for sale for £6m casting uncertainty over the project.

Setha Canterbury was leading plans to transform the city’s former Nason’s department store into a Brighton Lanes-style retail arcade, with a food and drink hall, public open space and 66 flats.

But the £30 million scheme has long been held up by concerns over wastewater pollution leaching into the Stodmarsh Nature Reserve in Canterbury.

Now, the firm is under the control of a receiver after defaulting on a loan taken out to buy and develop the scheme.

With the lender now seeking to recoup its cash, the project – previously described as a “once-in-a-lifetime” operation – has been listed on the market.

Estate agent GLPG confirmed any party wishing to take over ownership of the site, including previous owner Setha, would need to part with £6 million.

The firm says its offering of the Biggleston Yard development is “an extremely rare opportunity to create a vibrant mixed-use hub within the city centre”.

Weeks after Setha was placed into receivership, it now faces the prospect of losing control of the project altogether.

Despite the listing, company boss Manuel Alsoni maintains he still hopes to salvage his vision by refinancing the debt with a new lender and pushing forward with the plans.

“We believe our scheme is still achievable and we are working hard to try and refinance the debt and pay off the current lender,” he told KentOnline last month.

“The fact is that it will be difficult to sell because any new owner will have exactly the same problems that we have, and retail investment has become more difficult to secure.

“To be honest, it’s been a nightmare that we could not predict when we took on the project. But I don’t regret it because we still hope we can redevelop this historic site as a flagship scheme and our plans have been widely praised.

“If we can refinance, our aim is to start demolition of some of the site as soon as possible because an extensive archaeological survey will be needed before any building work can take place.”

The eye-catching proposals were first unveiled in 2019 - a year after the long-running family store closed its doors, blaming “brutal trading conditions”.

But like many proposed new developments across east Kent, the project was initially stalled by Natural England putting a block on residential schemes due to nitrates and phosphates from waste water polluting the Stodmarsh Nature Reserve in Canterbury.

However, Setha finally secured planning permission in 2022 after proposing a “solution” to the issue that involved installing an on-site sewerage pre-treatment plant and having waste tankered away daily.

But Mr Alsoni says the cost of the plant, as well as the heavy service charges that would need to be imposed on future residents, has since made this option unviable.

It now leaves his firm waiting for a broader - and cheaper - solution to emerge to appease Natural England, while continuing to search for new financial backers.

Leading city councillor Michael Dixey has urged those involved to resolve the matter as quickly as possible – but admitted it would not be a simple fix.

The Canterbury City Council cabinet member for property and performance told KentOnline: “It's disappointing to see any company struggle but this is a particularly important one for Canterbury.

“I think there's no difference between councillors, officers and the general public’s view on this – and it is definitely becoming an eyesore.

“But the Stodmarsh issue, of course, is preventing any building of flats or residential within a city which is not going to make it attractive to a would-be buyer.”

According to Companies House, a receiver from FRP Advisory Trading Ltd was appointed for Setha Canterbury Ltd in April following a submission by the lender, TAB London Ltd, which is seeking to recover millions of pounds.

Mr Alsoni believes if he can kickstart the scheme, there could be the potential to open up the ground floor of the building as a London Borough Market-style venue in the interim, which he hopes to discuss with the city council.

He says the wider project would take about two to three years to complete and would be financed with a development loan, which is common practice for such schemes.

Canterbury City Council says it is continuing to work flat out to find a solution to the Stodmarsh issue, which is also currently blocking more than 7,000 homes from being built.

Spokesman Leo Whitlock explained: "We recognise just how important the redevelopment of the Nasons site is to the health and vitality of the city centre.

“It is why we, as the local planning authority, granted planning permission for the scheme so it could kick into life once a way to protecting the Stodmarsh nature reserve is found.

"We are working closely with Kent County Council, Ashford Borough Council and a number of other Kent councils to find an answer to this problem and are straining every sinew.

"That includes the possible creation of wetlands or water meadows that could clean the water as it passes through the system, exploring ways of reducing waste water coming from council homes and pushing the water companies to upgrade their waste water treatment works as quickly as possible.

"And we are in constant dialogue with the government in all of its guises - Defra, DLUHC, Natural England, the Environment Agency and Downing Street - to find a way through.

"Indeed, between us, we secured almost £10m from central government to help us find an answer across the whole catchment with the eventual aim of restoring conditions at Stodmarsh."