* Turkey is to boost its stake on the expense of Statoil,Total
* Statoil, Total may withdraw from the project
* Shah Deniz II investment decision to be announced onDec.17
By Nailia Bagirova
BAKU, Dec 10 (Reuters) - Turkey is expected to increase its20 percent stake in the multi-billion dollar Trans-Anatoliannatural gas pipeline project (TANAP), designed to reduceEurope's reliance on Russian gas, Azeri state energy companySOCAR said.
Rovnag Abdullayev, head of SOCAR, said on Tuesday thatTurkey's stake would be increased at the expense of stakesoffered to Statoil and Total.
"The issue of how much Turkey's stake will be increased isunder discussion now with other members of the consortium,"Abdullayev told journalists.
BP has agreed to join SOCAR and Turkey in TANAP,which would carry Azeri gas to Turkey and to other markets inEurope, by buying a 12 percent stake from Socar, industrysources and energy officials told Reuters last week.
That stake is estimated to cost $8 billion to $10 billion.
TANAP is planned to start carrying 16 billion cubic metres(bcm) of gas a year in 2018 or 2019 from Azerbaijan's Shah DenizII field in the Caspian Sea, one of the world's largest gasfields.
It will be built from the Turkish-Georgian border toTurkey's border with Europe, with its preliminary total costestimated at $20 billion.
SOCAR currently has an 80 percent interest and Turkey theremaining 20 percent.
SOCAR in November 2012 proposed selling 29 percent of TANAPto Norway's Statoil, France's Total and BP, which are allmembers of the Shah Deniz II consortium.
BP and Statoil were each offered 12 percent, and Total wasexpected to buy 5 percent. But the sources say Statoil and Totalcould opt to buy smaller stakes or withdraw from being partnersin TANAP.
The sources said BP, meanwhile, is considering a furtherboost to its stake on top of the 12 percent agreed.
Abdullayev also said on Tuesday a final investment decisionon Shah Deniz II would be made on Dec. 17, when members of theconsortium and its partners will sign 39 documents.
Earlier this year, SOCAR and its partners in Shah Denizselected the Trans Adriatic Pipeline (TAP), which will connectwith TANAP at Turkey's border Europe to carry the Azeri gas toEurope.