A Telstra outage which left bank and retail customers stranded at ATMs and checkouts will be fixed soon, the telco giant says.

The nation’s big four banks and major supermarkets were among those hit by Thursday’s failure.Telstra provided an update shortly before 7pm, saying most services had been restored.

“We continue to investigate the issue affecting data services,” a Telstra spokesman said. “Many of our services are starting to restore. We’re sorry for any issues caused and will provide an update when we know more.”

The company is still investigating the cause of the outage.

The Commonwealth Bank said earlier on Thursday it had been “impacted by an issue” with a telecommunications provider. ANZ and Westpac also tweeted that a telecommunications outage was affecting their Eftpos systems.

CBA said it was affecting ATMs, Eftpos and some in-branch services, but NetBank and the CommBank app were still functioning.

St George tweeted it was also hit by the outage.

“We’re aware some branches, ATMs and services in Sydney metro are non-operational due to a broader network failure in the region,” St George Bank said.

Caltex and Woolworths also reported issues with their payment systems.

“Stores are continuing to trade as our teams are still able to process payments manually at this time,” Woolworths tweeted. “We’re working closely with Telstra to rectify the issue as quickly as possible.”

In the Sydney Town Hall Woolworths, staff had resorted to signs telling customers they could only accept cash.

Some on Twitter also reported Eftpos outages at McDonald’s, with varied results.

with agencies