A final decision on which pipeline will transport Caspian natural gas from the giant BP PLC (BP.LN)-led Shah Deniz offshore project to Western Europe will be based on which of the two mooted routes offers the best tariff level, BP Chief Executive Bob Dudley said Tuesday.

A decision on whether to back the Nabucco West pipeline concept or the rival Trans-Adriatic Pipeline is expected to occur in the second quarter of next year and will be based purely on which option delivers the best returns, Mr. Dudley said. "The rationale for the decision...will be purely economic," said Mr. Dudley.

Nabucco West last month won the right to be paired off in a two-horse race with TAP for the right to export gas from
Azerbaijan 's Shah Deniz gas field to customers in Europe .

Nabucco is a joint venture involving
Germany 's RWE AG (RWE.XE), Austrian oil firm OMV AG (OMV.VI) and Hungary 's Mol Nyrt. (MOL.BU). Other partners include Bulgargaz EAD, Transgaz SA and Boru Hatlari ile Petrol Tasima AS.

TAP is planned by EGL AG, Statoil ASA (STO) and E.ON Ruhrgas AG.