'BETRAYED' workers at BMW's Mini production plants have threatened to walk out over pension changes that could leave them thousands of pounds out of pocket.

Union bosses at Unite said they had tried negotiating with plant owner BMW but the carmaker was 'ploughing ahead' regardless.

A spokesman confirmed the union was now preparing to ballot members for strike action that could take place in the coming months.

It comes after warnings that proposals to end the final salary pension scheme for about 2,000 people could leave some workers losing six-figure sums.

BMW argues the change is necessary to address a pension scheme deficit.

But Tony Murphy, Unite's national officer for the automotive industries, said: "BMW’s UK workforce has worked hard to help deliver record profits in excess of £5 billion for the carmaker.

"They feel betrayed by its decision to close their final salary pension scheme, which will rob them of the future retirement they have worked hard for.

"Unite has tried to negotiate with the company in good faith and put forward proposals to keep the pension scheme open.

"To our bitter disappointment the carmaker has not returned that good faith and is instead ploughing ahead.

"Unite is now making arrangements to hold a full statutory industrial action ballot which, given the strength of feeling, could result in industrial action in the coming months.

"We would urge BMW bosses to recognise this by negotiating meaningfully over keeping the pension scheme open and honouring their pensions promises."

A consultation on the pension changes is currently taking place and ends next Tuesday.

The proposals would see the current ‘final salary’ pension scheme end, with workers instead moved to a ‘defined contribution’ scheme.

This would mean the maximum pension an employee could receive would fall from 40 per cent of their wage to 26 per cent.

In a letter to union members, Mr Murphy said Unite had asked BMW to provide its response to the consultation but bosses claimed to have not made a decision and instead suggested another meeting in February.

A BMW Group spokesman said: "The company is aware of Unite’s decision to hold a ballot for industrial action, however it is still consulting with its employee representatives regarding the proposal to close its two UK defined benefit pension schemes to future accrual and no decisions have yet been made."