MILLWALL chairman John Berylson says the "long-term future of the club" has been put at risk by Lewisham Council's deal with a property developer.
The Council have agreed to hand over three pieces of land around The Den, currently leased to the Lions, to Renewal, the company behind the 2,500-home Surrey Canal Project.
The car park, a space behind the stadium and the Lions Centre are all under threat.
Millwall have a long lease on the car park and the area behind the ground, while the Millwall Community Scheme has a shorter lease on the Lions Centre.
Renewal and the Council have exchanged contracts on the sale of the freehold of these sites.
The Lions claim the Council refused to consider their own plans for the land, which they say could provide the club with the opportunity to generate non-football revenue in the future.
The club's plans, which were presented to the Council last August, included a hotel, offices, sports and health facilities and flats.
However, the Council have pressed ahead with Renewal – and refused to disclose the terms of their agreement with the developer, making it difficult for Millwall to present a rival bid.
Berylson said in a statement: "I am appalled and bewildered by the behaviour of the council towards Millwall Football Club, our fans and our Community Scheme.
"Millwall has always been a club rooted in its community.
"It launched and supported the Millwall Community Scheme Trust almost 30 years ago which has helped thousands of young people over the years and the Club was proud to be at the forefront of the Save Lewisham A&E campaign.
"Lewisham Council's decision to sell the freehold of these three areas of land adjoining our stadium – including the Lions Centre and our car park – to developers without considering our own plans makes us feel isolated, unsupported by our local authority and angry.
"If these land sales go through, they will put the long-term future of the Club at risk because non-football assets that we hold in our leases will be surrendered to a developer.
"We have the long-term interests of the Club and the community in mind. Renewal does not. Lewisham Council must be urged to think again."
A spokesman for the Council said: "The land leased to Millwall and the Millwall Community Scheme is owned by the Council and we have been in discussion with them for many years.
"We have undertaken to safeguard their futures on many occasions and we continue to meet and discuss issues of concern with them.
"We remain absolutely committed to ensuring that the comprehensive regeneration of the Surrey Canal site takes into account the long-term future of the football club including any future requirement for stadium expansion, as well as infrastructure.
"We have also undertaken to ensure that the Millwall Community Scheme will remain close to the club and continue to be able to serve the communities of Lewisham and Southwark.
"The scheme will mean a greatly improved setting for the club and will breathe new life and vitality into this part of central London.
"The freehold sale safeguards the future of the club."