LG Electronics Inc, the world's No. 3 mobile phone maker, on Wednesday launched a smartphone based on Google's Android operating system in South Korea, as it seeks to boost its relatively weak smartphone line-ups.

LG, which is fighting an uphill battle against leaders Nokia, Blackberry maker RIM and Apple, plans to boost smartphone offerings with some 20 models this year, half the offerings based on the most popular Android.

The South Korean firm wants to claim a double-digit share of the global smartphone market by 2012. Currently the top three players control three quarters of the booming and lucrative smartphone market.

The model LG-KH5200, which will be sold by the country's second-largest mobile carrier KT, will compete against Motorola's Android-based smartphone MOTOROI launched earlier this year through top carrier SK Telecom.

Samsung Electronics, the world's No.2 mobile phone maker, is also set to unveil Android phones this month.

LG's smartphone with 3-inch full touch screen, 5 megapixel camera, and slider qwerty keyboard will cost around 650,000 won ($573).

LG hopes to defend sliding phone margins with premium smartphone offerings after it saw phone business profit margins falling close to zero in the December quarter as it had to spend heavily on marketing of its simpler models.

LG and its home rival Samsung together corner more than 30 percent of the global cellphone market, but they have struggled to muscle into the booming and lucrative smartphone market.

Samsung said last month it plans to treble smartphone shipments in 2010.

LG aims to sell 140 million mobile phones this year, versus 117 million sold last year to claim about 10 percent of the global market.

Shares in LG fell 0.5 percent to 103,500 won by 0020 GMT, versus a 0.2 percent drop in the broader market.

(Reporting by Miyoung Kim; Editing by Ken Wills)

($1=1133.6 Won)