Optus’ national phone and internet outage in late 2023 and currency fluctuations have been blamed for falling profits at telecommunications group Singtel, which disclosed the fiasco cost it $61 million.

Using actual currency rates, Optus’ revenue slid 5.4 per cent in the three months to December 31, while earnings before interest, tax, depreciation and amortisation dropped 1.8 per cent to $S465 million ($528 million.) Using constant currencies, December quarter EBITDA was up 1.7 per cent.