The $1.5-billion pipeline, which is being built by the Turkish holding Calik Energy and Italy's ENI, will extend 700 kilometers (435 miles) through Turkey from the Black Sea port of Samsun to the port of Ceyhan on the Mediterranean.
"The project to construct the Samsun-Ceyhan oil pipeline will contribute to Turkey's plans to become an international oil and gas transportation hub," local television cited Turkish Energy Minister Hilmi Guler as saying.
Guler attended the launching ceremony along with Italian Economic Development Minister Pierluigi Bersani.
The pipeline is scheduled for commissioning in 2011 and its projected capacity will be 60-70 million tons of oil a year (1.2-1.4 million bbl/d).
The project is designed to reduce the oil transportation load on the Black Sea Strait of Bosporus and the Dardanelles on the Marmara Sea, which handles some 150 million tons (1.1 billion bbl) annually.