Customers walk out of an Optus telecommunications retail store in the central business district of Sydney, Australia, Oct 5, 2022. (PHOTO / AP)

SYDNEY - More than 100,000 current and former customers have joined a class action lawsuit against Australian telecommunications giant Optus over a cybersecurity breach last year that compromised roughly 1.2 million customers, lawyers said on Friday.

Starting with the Optus breach in September, a spate of cyber attacks on Australia's corporate sector has exposed data from tens of millions of customers online and led the government to set up a new cyber security body and overhaul rules the home minister has called "bloody useless".

Major firms like top grocer Woolworths Ltd, and telecoms like Telstra and TPG Telecom have reported data breaches and unauthorized access, bringing to light corporate vulnerability to cyber attacks.

The Australian government is planning to set up an agency coordinating cyber security tasked with ensuring government agencies work together during cyber incidents as well as overseeing the government's investment strategies on cyber security

The Australian government is planning to set up an agency coordinating cyber security tasked with ensuring government agencies work together during cyber incidents as well as overseeing the government's investment strategies on cyber security.

A claim lodged in the federal court by Slater and Gordon on Friday alleged Optus breached laws and its own policies by failing to adequately protect customer data and destroy or de-identify former customer data, according to a release from the firm.

READ MORE: Australia's Telstra hit by data breach, 2 weeks after Optus

Optus, a unit of Singapore Telecommunications Ltd, said in an exchange filing that it had not yet been served with any court documents on the matter, and reiterated it would defend itself in the class action.

The class action members want compensation for the time and money required to replace identity documents and for distress, frustration and disappointment caused by the breach. The release did not specify an amount.

Claimants include a stalking victim who fears her life has been put in danger, the release said. Slater and Gordon Class Actions Practice Group Leader Ben Hardwick said the breach had potentially put vulnerable customers at risk of domestic violence and other crimes.

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"Very real risks were created by the disclosure of this private information that Optus customers had every right to believe was securely protected by their telecommunications and internet provider," Hardwick said.