ISTANBUL - The Qatar Investment Authority (QIA) has bought a stake in the Eurasia Tunnel company in Istanbul from the South Korean partner in the venture, SK Group, a statement by the Turkish Competition Board showed on Tuesday.

The competition board decision, taken on Sept. 8 and posted on its website on Monday evening, showed that QIA had bought the shares via its unit QH Oil Investment LLC from SK HoldCo Pte.

"It was decided that the investment in the tunnel company - Avrasya Tuneli Isletme Insaat ve Yatirim A.S. (ATAS) is not within the (board's) scope," the statement on the website said.

It did not specify how big a stake was purchased by the Qatari company.

ATAS was established in 2009 to build the Eurasia Tunnel project, a road tunnel built to connect the European and Asian sides of Istanbul, with Turkey's Yapi Merkezi and South Korea's SK E&C as equal partners in the venture.

(Reporting by Ebru Tuncay and Ali Kucukgocmen; Writing by Daren Butler; Editing by Ece Toksabay)