In April, Britain's biggest union said it would hold a total of eight strikes, including at the Mini and Rolls-Royce factories, but suspended further action last month to allow staff to vote on a revised deal.

The offer still proposed closing the scheme but offered a cash payment of 22,000 pounds over three years or 25,000 pounds paid into a new defined contribution pension scheme, Unite said on Monday.

Nearly 57 percent of members who voted turned down the deal and union officials will now meet on Tuesday to discuss what next steps to take.

"We would urge BMW bosses to reflect on the result and listen to the workforce by further engaging in meaningful talks with Unite," National Officer for BMW Fred Hanna said in a statement.

BMW said it was disappointed by the result and would be meeting with union officials soon.

"We believe the offer, which resulted from lengthy negotiations with the union since September last year, was fair," a spokeswoman said in a statement.

"It was designed to improve competitiveness which is in the long-term interests of all our employees in the future."

(Reporting by Costas Pitas; Editing by Paul Sandle and Mark Potter)