Prison officers have massively rejected the Government's controversial public sector pension reforms, raising the threat of an industrial dispute.
The Prison Officers Association (POA) said its members had made clear their opposition to paying more, working longer and receiving less pension.
The union said prison officers had voted against the proposals on a "massive scale".
General secretary Steve Gillan said: "I want to be absolutely clear to Government - your proposals, as they stand, have been totally rejected by the POA throughout the United Kingdom.
"Make no mistake, this is a landslide rejection and the membership have expressed their views loud and clear. We will take any and all appropriate action deemed necessary to oppose these initial proposals to safeguard our pension provision."
Talks between the Government and unions on reforming public sector pensions are to continue into the autumn, it was announced earlier this week.
Negotiations will now be split to cover different schemes, such as those in local government, the NHS and the civil service.
A national strike was held last month by teachers and civil servants in protest at the planned changes and there have been warnings of an autumn of discontent.
The discussions will start by the end of the month and be completed by the end of October, and will be centred on the target of £1.2 billion-worth of savings for 2012/13, although the Government stressed it remained committed to securing savings of £2.3 billion in 2013/14 and £2.8 billion in 2014/15.