UPDATE 1-Thai mobile firm AIS to spend $1.1 bln on 3G, 4G expansion

* Expects to invest 20 bln baht each on 3G and 4G LTE network

* Aims to expand 4G coverage to 72 provinces by May

BANGKOK, Jan 26 (Reuters) - Advanced Info Service Pcl (AIS) , Thailand’s largest mobile operator, said on Tuesday it expected to invest a combined 40 billion baht ($1.11 billion) this year on expanding 3G and 4G LTE mobile networks to retain its market share.

AIS, 23 percent owned by Singapore Telecommunications Ltd , planned to spend 20 billion baht on the 3G network and another 20 billion on the 4G network, Chief Executive Somchai Lertsuthiwong told a news conference.

4G LTE, a wireless connection that allows faster speeds of data download, is seen as key growth driver for Thai mobile operators which suffered a continued drop in voice services in a slowing economy.

After winning a licence for 4G spectrum in an auction in November, AIS spent 14.5 billion baht on installing 7,000 base stations within two months as it accelerates network rollout to compete with rivals, Somchai said.

AIS, which lagged second-ranked Total Access Communication and True Corp on 4G services, officially launched the super high-speed services in 42 provinces on Tuesday, he said.

The company aims to expand 4G coverage to 72 provinces by May, Somchai said, adding AIS’s board will approve the final investment budget for 2016 along with its financial results next month.

AIS has 38 million subscribers, of which more than 20 million surfed Internet via mobiles.

As Thais spend an average five hours a day on mobile and watch more than 10 million videos a day, Somchai said AIS offered the country’s fastest speed at 150 Mbps.

AIS also joined forces with China’s Huawei Technologies Co to develop new super high-speed LTE-enabled mobile phones, to be commercially launched at the end 2016, Somchai said. ($1 = 35.9800 baht) (Reporting by Khettiya Jittapong and Manunphattr Dhanananphorn; Editing by Muralikumar Anantharaman)