* 4G auction terms to be reviewed for more transpanrency
* AIS shares down 3 pct, True surges 11 percent (Adds AIS comments, updates share prices)
By Khettiya Jittapong
BANGKOK, June 17 (Reuters) - Thailand's telecommunications regulator said on Tuesday that it has suspended temporarily an auction of fourth-generation (4G) mobile licences as requested by the military council now ruling the country.
The 4G spectrum will enable companies to tap more revenue from fast-growing data services and reduce regulatory costs under a new licencing regime.
The auction is being delayed as more time is needed to work out the details of the process, as well as to ensure transparency, the National Broadcasting and Telecoms Commission (NBTC) said in a statement.
The regulator had planned to hold an auction for a 25 MHz block on the 1800 MHz spectrum in August and a 17.5 MHz block on the 900MHz band in November or December.
Shares in Advanced Info Service, the country's largest mobile operator, extended their losses and fell 3 percent after the announcement.
AIS, 21 percent owned by Singapore Telecommunications , is the only operator without a 4G service while it has the highest number of customers owning 4G-enabled devices.
"There is no clarity about how long the suspension will be. If it is delayed until next year, it could have some impact," Wichian Mektrakarn, AIS Chief Executive told Reuters, adding that the market leader has not revised its business plan or concluded its investment for 4G.
Analysts had said a successful auction could help AIS achieve spectrum dominance over rival True Corp, which has a leading position in the 3G market.
Pakorn Pannachet, chief marketing officer at second-ranked Total Access Communication (TAC), said the suspension will have limited impact in the short term given the company has sufficient frequencies to operate.
TAC is controlled by Norway's Telenor.
China Telecom is in the process of buying a 18 percent stake in True, which runs the country's third-largest mobile network.
On Tuesday, TAC shares closed 2.6 percent lower, while True jumped 10.9 percent. The overall Thai index was 0.06 percent lower. (Additional reporting by Manunphattr Dhanananphorn; Editing by Matt Driskill and Ryan Woo)