The tender for the project marks a further step toward finalising the design of the 3300 kilometre pipeline, which has been criticised for taking too long to plan with no reliable timetable for gas supplies.

The rough route of the €4.6 billion ($6.19 billion) pipeline is already fixed, but the final design decision is expected for next year.

Ahead of the final design decision, the Nabucco group shortlisted companies to submit their bids for the final route, allowances for construction and expropriation of real estate along the pipeline as well as the planning of underground and above ground plants, said Saltuk Duzyol, acting general manager at Turkey's state-run Botas.

"All