A number of new devices have been unveiled by technology companies at industry exhibition Mobile World Congress, which takes place in Barcelona this week.

Controversial Chinese IT firm Huawei earlier launched what it claims to be the lightest seven-inch tablet computer on the market.

Huawei's new MediaPad X1 weighs 239 grams and is just 103.9mm wide and 7.18mm thick.

The new device, which it is thought will offer an unprecedented three-and-a-half days of battery life, will reach stores in August.

Huawei has previously faced harsh criticism over its close ties to the Chinese government and has been described by officials in the US and Australia as a national security threat.

"Huawei X1 is our premium line tablet, it has a 13 mega-pixels camera, it has a seven-inch display, it is the thinnest tablet in the world, it is 7.18 mm," said Huawei spokesman Laimonas Petruseviius.

Separately, struggling phone maker BlackBerry has signalled a return to its roots after it announced plans for a new "retro" handset that will revive features from its original line of devices.

The phone will be known as the BlackBerry Q20 and will boast a tactile keyboard and trackpad, according to BlackBerry boss John Chen.

"Virtually everyone I meet says they love our keyboards. I call it the 'BlackBerry Classic'," said Mr Chen.

The Canadian firm also unveiled plans for a budget handset intended to ratchet-up sales in the booming Southeast Asian mobile market.

Mr Chen said that the phone, to be known as the Z3, will sell for less than €150.

The device will launch in Indonesia in April before it is rolled out across the rest of Southeast Asia, Mr Chen told reporters.

The announcements mark the beginning of an ambitious plan intended to return the firm to profitability by cutting manufacturing costs and increasing lucrative government sales.

Meanwhile Chinese handset maker Gionee has announced what it claims is the world's slimmest mobile phone at an annual industry gathering in Barcelona.

The Gionee Elife S5.5, which will hit shelves in India and China next month, is just 5.5 mm wide and boasts a 5-inch, full HD screen alongside a 13-megapixel camera.

"We believe smartphones are both consumer electronics products and decorative artworks. A new approach with a focus in design is needed," said Gionee president, William Lu.

"We explored the design aesthetic of the smartphone from the standpoint of the fashion origins, emphasising smartphones as a stylish identity for end users."

Winners announced at Global Mobile Awards

Earlier, the winners of the 19th Annual Global Mobile awards were announced by the GSM Association, which runs Mobile World Congress.

HTC’s One handset was named Best Smartphone, while Apple’s iPad Air was named Best Tablet.

Nokia picked up two awards, with its Lumia 520 being named Best Low-Cost Smartphone and the Nokia 105 chosen as Best Entry-level or Featurephone.

LG was named Most Innovative Device Manufacturer of the Year.

The shortlist for the 'Best New Mobile Handset, Device or Tablet at Mobile World Congress 2014’ will be announced tomorrow, with the winner being chosen on Thursday morning.