The threat of industrial action drew nearer at Cadbury yesterday, as workers vented their anger at plans to move production to Poland.

Around 1,600 members of the Unite union - including hundreds based at the Bourn-ville plant in Birmingham - took part in a vote on the company's plans to close a site near Keynsham, and move some Bournville lines to a factory in Warsaw.

They voted 9-1 to reject the company's outsourcing plans, and 8-1 to take part in a strike ballot if it became necessary.

Union leaders met the management team later in the day to ask them to reconsider their plans, which would see 700 jobs lost in the UK - including 200 at Bournville.

But a spokesman for the union said they had not yet received any assurances from Cadbury that the move was the best course of action to take.

"We are pressing the company basically for a detailed rationale of what they are doing in terms of closing the factory and moving work to Poland.

"We are not satisfied with the detail and level of financial information we have been given by the company."

He added that the seriousness of the proposals - which would affect almost half of the total Cadbury's workforce - was what made workers so keen for answers, and what had made voters so vocal in their condemnation of the company.

Unite national officer Brian Revell said: "Cadbury prides itself in being a company that listens to its consumers, shareholders and the City. This vote shows it must listen to its workforce too."

A Cadbury spokesman said: "We are aware of the ballot results, but it is important to point out that this was for consultation only, and there is no industrial action planned."