HTC CEO Peter Chou shows the new HTC one (M8) phone during a launch event in New York, March 25, 2014. [Photo/Agencies]

HTC Corp unveiled a new flagship smartphone on Tuesday, an upgrade to the award-winning HTC One that it hopes will claw back some of the market share lost to Samsung.

The HTC One M8 has a 5-inch display, slightly larger than its predecessor, as well as improved camera technology, a faster processor and updated software, the company said.

Chairwoman Cher Wang said at an event in London that the new device, which has a premium metal body, was an evolution of last year's HTC One.

The HTC One was lauded by critics, she said, and it was still winning awards, including "Smartphone of the year" at the Mobile World Congress in February.

"The best smartphone in the world gets better in every way," she said of the new model.

But HTC One - the group's biggest selling model to date - was not enough to stop more than two years of sliding sales as the company battled rivals such as Apple and Samsung - the market leader in terms of sales.

Just over two years ago HTC supplied one in every 10 smartphones sold around the world. In 2013 its global market share had fallen to just 2 percent, according to Strategy Analytics analyst Neil Mawston. The drop in its share price has also been precipito us.

Its latest sales figures, for February, were 36 percent lower than a year ago.

It is fighting back with a new line of cheaper handsets, including a mid-tier handset unveiled in Barcelona last month, as well as the HTC One M8.

Analysts at CCS Insight said the HTC One M8 was a "make-or-break" device for HTC.

"The company has learned lessons from the phone's well-received but underperforming predecessor," they said.

"HTC must capitalize on the phone's distinctive design and premium materials to re-establish itself in the market."

They added that the device would start selling almost immediately, beating new flagship models from Samsung and Sony to the punch.