Troubled support services group Interserve has pushed back the announcement of its interim results to the end of this month as it tackles accounting irregularities in its industrial services business.

An Interserve statement said: “Following the announcement of a review of accounting misstatements in its industrial services division, Interserve is postponing the announcement of its interim results in order to allow time to verify the adjustments needed.” It had been expected to announce its results on Monday.

The irregularities, which are understood to cover at least five years, were discovered during an internal restructuring.

Interserve suspended six staff after the discovery.

Shares in the company fell 13.75p to 260p after the announcement. The group believes correcting the issue will lead to a £25m reduction in net assets in its half year results.

It also understood that the support services group faces possible legal action from shareholders. Accountant KPMG and law firm Linklaters are carrying out an independent review of the accounts.