South Africa's retailer Steinhoff said on Thursday that an investigation by auditors PwC has found that the overstatement of its profits may result in additional material impairments, sending its shares more than 13 percent lower.

Steinhoff, which runs chains such as Britain's Poundland, Mattress Firm in the U.S. and Conforama in France, is fighting for its survival after discovering irregularities in its accounts in December.