Customers with smart meters who sign up for Origin Energy's online portal must consent to their data being shared with a string of third parties. The data is stored in Australia but shared with US company Tendril, which is described by Origin as a smart energy technology provider.

Australia's privacy watchdog said the technology could threaten people's privacy. ''We are starting to see people voicing concern about the level of data that these meters can collect,'' federal Privacy Commissioner Timothy Pilgrim said.

Mr Pilgrim said electricity companies had a legal responsibility to delete or ''de-identify'' personal information that was no longer needed. However, an Origin spokesman said the company kept former customers' data for retrospective queries and ''tax and compliance purposes''.

The state government aims to install smart meters - which log electricity use every half-hour - in all Victorian homes by the end of next year.