Angry Cadbury workers have demanded hedge fund boss Nelson Peltz and the Qatari state investment fund stop interfering with Cadbury Schweppes.
They accused Mr Peltz, whose Trian Fund Management - which includes the Qataris - owns 4.5 per cent of the firm, of creating an environment in which British jobs are being put at risk.
Unite national organiser for the food industry Brian Revell said statements by Nelson Peltz about 'becoming more active as a large shareholder' in Cadbury's affairs were destabilising the company.
On Tuesday Mr Peltz called on Cadbury's board to increase shareholder value by setting near term margin targets and long term goals for its confectionary business.
Mr Revell said: "Nelson Peltz and his Qatari friends are interested only in the short and medium term profits they can squeeze from Cadbury Schweppes.
"He has no concern for the workforce or their communities.
"We believe that company's directors must stand up to Mr Peltz and his Qatari friends.
"At the time when this unwelcome interference is taking place, we are faced with an outrageous plan to close Cadbury's Keyn-sham factory near Bristol and transfer production to Poland.
"There is no doubt that this plan reflects the approach of vultures like Nelson Peltz, and Cadburys must reconsider the proposal before it damages the market share of a popular British product."
Meanwhile, campaigners against plans to close Keynsham near Bristol sang Christmas carols yesterday to protest against the move.
Around to 50 Unite union members from Cadbury's sites in Bristol and Birmingham joined together to sing outside Cadbury World in Bournville.
But instead of humming the traditional festive carols, the protesters changed the lyrics to "reflect the anger of workers".
The words for Oh Christmas Tree were changed to "George Cadbury George Cadbury is turning in his grave".
Spokeswoman Lydia Hayes said: "We've had a really good turn-out. It's gone really well."
The protesters also sang outside the Bourn-ville factory and at the Cadbury social club.
Cadbury plans to shut the plant at Keyn-sham, near Bristol - with the loss of hundreds of jobs - and transfer production to Poland.
Up to 500 jobs are set to be axed.