Wrightbus is imposing a recruitment freeze as part of a “rationalisation plan”, according to the BBC.
A company memo sourced by the broadcaster states that the group board is finalising changes to its “organisational structure”.
It said this was in response to “challenges in both the local and overseas markets”.
The group’s last financial figures, for 2014, showed it made an annual profit of £14.5m on a turnover of £297m.
The letter added that the changes, which will reduce operating costs, will be communicated to staff in coming weeks.
The company said it had no comment to make but it is understood the move is about maintaining competitiveness rather than dealing with any particular issue.
Wrightbus employs more than 1,500 people.