* 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 on Dec.17
By Nailia Bagirova
BAKU, Dec 10 Turkey is expected to increase its 20 percent stake in the multi-billion dollar Trans-Anatolian natural gas pipeline project (TANAP), designed to reduce Europe's reliance on Russian gas, Azeri state energy company SOCAR said.
Rovnag Abdullayev, head of SOCAR, said on Tuesday that Turkey's stake would be increased at the expense of stakes offered to Statoil and Total.
"The issue of how much Turkey's stake will be increased is under 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 in Europe, by buying a 12 percent stake from Socar, industry sources 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 Deniz II field in the Caspian Sea, one of the world's largest gas fields.
It will be built from the Turkish-Georgian border to Turkey's border with Europe, with its preliminary total cost estimated at $20 billion.
SOCAR currently has an 80 percent interest and Turkey the remaining 20 percent.
SOCAR in November 2012 proposed selling 29 percent of TANAP to Norway's Statoil, France's Total and BP, which are all members of the Shah Deniz II consortium.
BP and Statoil were each offered 12 percent, and Total was expected to buy 5 percent. But the sources say Statoil and Total could opt to buy smaller stakes or withdraw from being partners in TANAP.
The sources said BP, meanwhile, is considering a further boost to its stake on top of the 12 percent agreed.
Abdullayev also said on Tuesday a final investment decision on Shah Deniz II would be made on Dec. 17, when members of the consortium and its partners will sign 39 documents.
Earlier this year, SOCAR and its partners in Shah Deniz selected the Trans Adriatic Pipeline (TAP), which will connect with TANAP at Turkey's border Europe to carry the Azeri gas to Europe.