In a move expected to reduce Europe’s dependence on Russian energy, BP and its partners have signed 25-year sales agreements with nine companies to take 10bn cubic metres a year (bcma) of gas from the field, which sits some 70km offshore in the Caspian Sea.

The consortium is working on the second stage of the field’s development, which is expected to add a total 16bcma of gas production to the roughly 9bcma coming from Shah Deniz Stage 1.

The $40bn project will bring gas directly from Azerbaijan to Europe for the first time, offering an alternative to Russian gas imports by linking energy-hungry European consumers with the country’s giant offshore gas fields.

While no UK companies are among the nine who have agreed supplies, BP says that by boosting European energy security the UK could indirectly benefit from the deals as North Sea reserves dwindle.

The gas will be carried by the Trans Adriatic Pipeline, which when completed in 2019 will run through Greece, Albania and then under the Adriatic Sea to western Europe.

The next step for the second stage of Shah Deniz field is for the companies involved to agree their final investments, with start-up expected in 2018.

The expansion has been years in the works, during which period the US shale revolution has unleashed vast volumes of cheap shale gas onto the market. However, BP said that demand for Shah Deniz output had been high, with total interest “three to four times” the 10bcma available.

Gordon Birrell, BP’s regional president in Azerbaijan, Georgia and Turkey, said: “The Shah Deniz consortium is proud to be involved in the conclusion of one of the biggest gas deals in the history of the oil and gas industry.

“The strong demand for Shah Deniz gas gives us confidence in the long-term development of Azerbaijan’s gas resources. Today’s signings represent another important milestone bringing us closer to a final investment decision on the Shah Deniz 2 project.”

BP has a 25.5pc stake in Shah Deniz, as does Norwegian energy giant Statoil. Other partners include Total, with 10pc.