Britain's biggest union, Unite, has come under fire as it ups the ante in its attack on food and drink manufacturers.

Unite was set to ballot members for strike action at Carlsberg UK following a dispute over job losses in distribution. And Cadbury workers are being balloted for a company-wide strike over a "reneged" pay deal.

But strike action would not be in workers' best interests, warned Food & Drink Federation HR director Angela Colehill.

"The predicted peak to in excess of three million unemployed may now be avoided. This is in part due to effective employee relations in the UK. Initiatives including pay freezes, cut-backs in the use of agency workers and reduced working hours have enabled our members to retain staff."

But the loss of flexibility amid industrial action put at risk the future viability of the UK's biggest manufacturing, Colehill added.

"One of the successes of the UK economy has been its flexible labour market and this needs to be safeguarded for our future competitiveness," she said.

Unite national officer for food and retail Jennie Formby said the union was happy to discuss efficiency, but said the sector could afford to protect jobs.

"Our members never take the decision to strike lightly," she said. "But companies such as Cadbury and Diageo are not struggling they're making strong profits. Job cuts are a short-sighted decision motivated by greed."

On Wednesday Unite held a protest at Diageo's AGM over proposals to cut 900 jobs at its Johnnie Walker bottling plant in Kilmarnock, Scotland.

"We know Diageo's shareholders want a strong business," stated a letter handed out at the protest.

"So do we, because strong businesses mean good jobs. But as shareholders, we think you also want one which can hold its head up high in the communities that have made you such good returns. Only this year the workforce agreed pay restraint, unpaid time off and short-time working in exchange for job security. Please do not repay this loyalty by slashing 900 jobs."