Mr Borisov is concerned that the contract will not be profitable for Bulgaria and is not in the national interest.

Mr Borisov has said that a number of government officials, including Minister for Economy and Energy Traicho Traikov are investigating whether technical amendments can be made to the contract, which does not allow any of the partners to withdraw from the contract.

Of the 278 km of pipeline, 166 km would pass through Bulgarian territory to bring more than 100 MMbbl of oil from the Black Sea to the Aegean Sea along an overland route that bypasses Turkey’s Bosporus and Dardanelles.

The project is expected to be completed by the end of 2011 or beginning of 2012.