The ASX has blamed an "unprecedented" hardware failure for its outage on Monday that forced the early close of trading, but hit back at any suggestion its handling of the meltdown prevented stockbrokers taking orders to rival Chi-X.

A faulty disk in its data centre and a secondary problem connecting its system to the backup data centre at Bondi meant the ASX's crisis plan was rendered ineffective. That led to the most serious failure by the ASX's systems since its outage of October 27, 2011. The offending piece of hardware was replaced on Monday night and the market reopened on Tuesday. Neither the exchange operator nor its vendor – who has not been named – had ever seen a malfunction of this nature before, ASX claims.