Optus will pay $6.4 million in penalties for misleading customers after the Federal Court found the telco had told more than 130,000 users that their existing broadband services were at immediate risk of disconnection when this was not the case.

In June, the Australian Competition and Consumer Commission (ACCC) took Optus to court claiming the company had been deceptive when it emailed 139,000 of its mobile internet customers last May telling them that their existing broadband services, which were supplied by Optus' competitors, would be "disconnected very soon" as part of the transition to the national broadband network.

Optus has copped a $6.4 million fine after the Federal Court decided its messaging was misleading. Credit:Optus

The email encouraged the users to switch their services to the Optus NBN offer.

The consumer watchdog argued the claims were misleading because many of these customers were not at immediate risk of disconnection.