Demand for the government's nascent national broadband network has been thrown into fresh doubt after it was revealed that the high-speed network launched in Melbourne by Telstra a year ago has only attracted 200 customers, despite being available to nearly one million premises.

Hackers have found a new weakness in earlier versions of Microsoft's Internet Explorer (IE) Web browsing software, which could be used to remotely seize control of computers from unsuspecting users.

The coalition will continue to oppose legislation that paves the way for Telstra to be broken up.