This should be dealt with IAS 8 - Accounting Policies, Changes in Accounting Estimates and Errors
IAS 8.42 is clear about such error correction method:
"...an entity shall correct material prior period errors retrospectively in the first set of financial statements authorised for issue after their discovery by:
(a) restating the comparative amounts for the prior period(s) presented in which the error occurred; or
(b) if the error occurred before the earliest prior period presented, restating the opening balances of assets, liabilities and equity for the earliest prior period presented."