Canadian modem and software company Sierra Wireless has unveiled what it claims are the world's first USB modems for use with HSPA+ internet networks.

The USB 306 and USB 307 offer download speeds of 21Mb, which Sierra suggests are the fastest speeds available from any current mobile broadband devices.

Greg Speakman, vice president of marketing at the firm, explained that the dongles have been developed in response to the way internet use has changed.

The improved download speeds and uplink speeds of 5.76Mb are designed to support increased demand for video and music downloads.

"We recognise that the way people use the internet has evolved," Mr Speakman said.

"Most people require higher bandwidth from their connections now than they did even two years ago. Sierra Wireless is working hard to stay at the forefront of mobile technology to ensure that our customers can get online and do whatever they need to do, whether from home, work, or somewhere in between."

The USB 307 is designed for use in Europe and will be demonstrated in Barcelona next week at the Mobile World Congress event.