The Royal Mail is forcing managers to reapply for their jobs, putting it on a collision course with a leading union and at risk of industrial action.
The state-owned postal service is reviewing its management structure, and has asked a number of managers to reapply as part of the process.
A spokesman said: "Royal Mail is facing tremendous challenges and changes. This effects everybody in the com-pany. Our managers, just as much as our postmen, are committed to making sure that we're delivering customer service and the right leadership.
"We're committed to supporting and developing all the people who want to remain in the business."
The Royal Mail has 1,500 delivery offices, each of which has at least one manager. Insiders say the Royal Mail is seeking only to shake up the management structure, and is not looking to cut jobs.
But Amicus, which represents Royal Mail managers, is worried that jobs will still be lost and has not ruled out industrial action.
Brian Scott, assistant national secretary, said the union had already held meetings with the Royal Mail but so far had failed to come to an agreement.
"We're objecting on the basis that members may end up out of work," he said. "It's also about being assessed for your own job, and we feel that's unnecessary. It's all unnecessary, costly and very concerning. We're hoping that [industrial action] won't be necessary, but it's something that we won't rule out.
"The discussions will continue over the next couple of weeks and then we will take stock and see where we are. We're not looking for trouble but it could ultimately lead to that," he said.
The Royal Mail has been through a dramatic transformation in the past few years. Under chairman Allan Leighton and chief executive Adam Crozier, the once-ailing business has been returned to the black. It also secured concessions from the Government, including using a previously ring-fenced £850m to prop up its gaping pension deficit and a cash injection to help modernise sorting systems.
But the process has not been without pain. Working practices have been overhauled and 30,000 jobs axed. Other changes included scrapping the second post and introducing new ways of charging for post.
Problems still remain. As well as its £5.6bn pension deficit, the Royal Mail's monopoly ended at the start of this year and it has locked horns with the Communication Workers Union, which also represents Royal Mail staff.
So far this year, the CWU has expressed concern and threatened action over pay levels and plans to offer shares in the company to staff, believing it is a step towards privatisation.
The Royal Mail spokesman said that the company would "continue to involve" unions in talks.