Blackberry on Friday reported losses worth 4.4 billion US dollars for the third quarter ending in November, sending shares plummeting by 7 per cent during pre-market trading.

The struggling Canadian smarthphone maker had already posted losses totalling 965 million dollars in the second quarter.

Intense competition from Apple's iPhone and Android and Windows smartphones are the source of its woes, with many Blackberry customers switching the other brands.

Worldwide revenues for Blackberry in the third quarter came in at 1.2 billion dollars, compared with 2.7 billion in the same period last year, as sales in the company's focus markets of Asia shrunk by half.

To right itself, Blackberry announced a number of initiatives, including company restructuring, thousands of layoffs and a five-year partnership with Taiwanese components manufacturer Foxconn.

"With the operational and organizational changes we have announced, Blackberry has established a clear roadmap that will allow it to target a return to improved financial performance in the coming year," said the company's chief executive officer, John Chen.

"But we still have significant work ahead of us as we target improved financial performance next year," he added. Part of Blackberry's stated strategy is to concentrate on corporate clients, particularly in fast-growing markets such as Indonesia and Mexico.

Having made a solid impact as smartphones first appeared on the market, Blackberry saw it share of the market decline with the 2007 advent of the iPhone.