UPDATE 1-KOGAS to seek $1.7 bln new share issue - official

* KOGAS to double capital to 8 trln won by 2012

* Considering investment in Siberian gas field

* Studying import of Siberia gas via LNG or pipeline

* KOGAS shares up 5.1 pct on gas hopes (Adds details with company confirmation)

SEOUL, Sept 29 (Reuters) - South Korea's state-owned KOGAS (036460.KS) plans to issue new shares worth 2 trillion won ($1.7 billion) and double its capital to 8 trillion won by 2012, a senior company official said on Tuesday.

The world's biggest corporate buyer of liquefied natural gas (LNG) is also considering investing in a gas field in Siberia, estimated to hold about 90 percent of Russia's natural gas reserves, said the official.

"We cannot delay the issuance too long as our new (resource development) businesses are scheduled to start at the end of this year and early next year," said the official, who declined to be identified.

Earlier, local media eDaily quoted KOGAS CEO Choo Kang-soo as saying it was considering issuing shares in domestic and overseas markets to raise capital.

The report added that the government was unlikely to subscribe to the new issue but would remain the major shareholder even after it. The government holds a 26.8 percent direct stake in KOGAS and another 24.5 percent through state-run Korea Electric Power Corp (KEPCO) (015760.KS).

Shares in KOGAS closed up 5.11 percent on Tuesday after the Maeil Business Newspaper said the company was considering investing in a gas field in Siberia. [ID:nSEO252213]

Separately Yonhap News reported KOGAS was planning to import Siberian natural gas in liquefied form, rather than via a pipeline that crosses North Korea as previously decided.

The official at KOGAS denied the report, saying it was still conducting a feasibility study on both options, which would be concluded by the end of this year.

KOGAS and Russia's Gazprom (GAZP.MM) last year agreed a $90 billion deal to import up to 10 billion cubic metres of gas a year, a fifth of KOGAS's needs, for 30 years after 2015 through a $3 billion pipeline that would run from Russia's Vladivistok across North Korea, which is technically at war with its wealthy southern neighbour. [ID:nLT479224] [ID:nSEO280350] ($1=1186.8 Won) (Reporting by Rhee So-eui and Cho Meeyoung; Editing by Jonathan Hopfner and Lincoln Feast)