• Chelsea Pitch Owners furious over bulk selling of shares • Belief that insiders are trying to force sale of Stamford Bridge

Chelsea's potential stadium move was at the centre of more controversy on Monday after another stormy meeting of Chelsea Pitch Owners.

The scandal over "dodgy" shares sold in CPO – the supporters-led group which has owned the freehold of Stamford Bridge since the 1990s – was compounded when they appeared to help swing a crucial vote that might have limited the power of shareholders to do just that.

The sale of shares in CPO had been suspended since Chelsea failed to convince the company to sell them back the land beneath their home at an extraordinary general meeting in October, something they need to do before they can move to a new stadium.

The build-up to that meeting saw CPO sell 1,686 more shares than they were entitled, something that provoked outrage among opponents of the club's plans. There were accusations associates of Chelsea employees, including those of the chairman Bruce Buck, had engaged in – perfectly legal – bulk buying in a bid to sway that vote and an internal investigation followed.

CPO announced they were powerless to revoke any oversold shares but promised to act to prevent a repeat, including attempting to reduce the voting rights of all shareholders from 100 to 10 votes, regardless of how many shares they held.

But that proposal was defeated at Monday's EGM, realising the worst fears of the club's opponents. That is because CPO shareholders also voted to reopen the sale of shares, effectively giving the green light to anyone to engage in bulk buying and influence potential future votes on the fate of Stamford Bridge.

There were audible gasps of "What?!" as the results were announced, with a leading opponent of Chelsea's plans, Paul Todd, angrily declaring: "I want to find out how many illegal shares voted."

Other shareholders had earlier voiced their concerns about just such an outcome during an EGM that at times descended into the kind of public slanging match that dogged the last two CPO meetings.

There were calls to adjourn the meeting and hold a fresh one to consider solely the issue of voting power before the sale of shares was reopened. But those calls were ignored, a move that proved decisive and sparked accusations the CPO chairman Steve Frankham had used his proxy votes to defeat the resolution.

But he insisted he had voted in favour as many times as he was permitted, pointing to a turnout of less than a third as the reason behind the outcome. "How many shares voted? 4,000? We have 15,000 shares out there. I urge Chelsea fans to vote," he told the Press Association.

Another resolution was passed authorising the CPO board to consider measures to prevent new shareholders attempting to profiteer from buying shares. But Frankham admitted he could not give a cast-iron guarantee that would also deny those with links to the club the chance to buy in bulk, saying: "We will endeavour to make sure that doesn't happen."

Chelsea, who have denied any wrongdoing throughout the stadium saga, have always maintained they have yet to decide whether to leave Stamford Bridge. However, they recently lost their battle to buy Battersea Power Station and turn it into a new 60,000-seater ground.