The competition watchdog has postponed its decision on whether to allow the Metcash-owned Mitre 10 hardware chain to buy Woolworths' Home Timber and Hardware stores.

The Australian Competition and Consumer Commission had been scheduled to announce its final decision on Thursday, but is considering an undertaking by Metcash in response to issues raised by the watchdog.

The ACCC says it has not set a new deadline to rule on the possible fate of Home Timber and Hardware stores, which Woolworths is offloading as it exits the hardware sector.