Unions have demanded a meeting with Kraft
A union representing Cadbury workers has called on US food giant Kraft to state its plans for the workforce if its takeover bid is approved.
Workers fear jobs could be axed if Cadbury's shareholders, as expected, support the takeover.
Unite said the company had to "come clean" and state its future intentions for the firm.
Jennie Formby, from the union, said: "Kraft can no longer hide behind the secrecy of UK takeover rules."
Last month, Unite warned Cadbury shareholders that Kraft's debts, estimated to be about £22bn, meant there could be an "irresistible imperative" to cut costs by cutting jobs.
Unions fear Kraft will move quickly to recoup the expenditure by slashing jobs and have demanded an urgent meeting with Kraft's global management.
Ms Formby, Unite's national officer for food and drink, said: "Our worry is that it will be the workforce who pays the price - and until Kraft tell us otherwise by making its plans clear, we have to presume we are now in a fight to protect jobs and investment."
Cadbury shareholders will vote on the revised offer from Kraft on Tuesday.
On the same day, Cadbury workers plan to head to Westminster to call for government support.
Jack Dromey, general secretary of Unite, said it feared the takeover was neither in the interest of Cadbury workers or the country.
He said workers were fearful they would share the same fate as Terry's of York, which was closed after being bought by Kraft and production moved abroad.
"Kraft cared little for the great history of that plant or for the skills of its workforce so we must seize the opportunity now to ensure that Cadbury and its workforce do not suffer the same fate," he said.
"The government must secure meaningful pledges from Kraft, and police them so that Kraft cannot again walk away from a UK workforce.
"Ministers must make it abundantly clear that closures and mass redundancies will not be accepted by the British government or the British people."
Kraft declined to comment.