Construction has started on the Trans Adriatic Pipeline (TAP), which will transport natural gas from the Shah Deniz II field offshore Azerbaijan to Europe.
The €5.6bn project is expected to supply around ten billion cubic metres of Azeri gas a year to European countries.
Operations from the 878km-long TAP are expected to begin in 2020.
TAP is the European section of the Southern Gas Corridor that aims to connect the EU market to new gas sources.
Greek Prime Minister Alexis Tsipras said: "The beginning of construction for the Trans Adriatic Pipeline, TAP, is taking place at a pivotal time for the Greek economy and our wider region.
"With regard to the project’s financial aspect, ensuring Europe’s energy supply, as well as diversifying its energy sources and routes constitute the foundation stone of both our country’s energy strategy and the overall European planning."
TAP managing director Ian Bradshaw said: "After winning the bid in 2013 and working diligently to prepare for this moment, we are delighted to have started constructing the pipeline – a strategic project for Europe transporting new sources of Caspian gas via a new route commencing in 2020 and for years to come."
"TAP will also help integrate and diversify Europe’s energy supply, making a significant contribution to improving its energy security."
The pipeline is proposed to link with the Trans Anatolian Pipeline at the Turkish-Greek border at Kipoi, across Greece, Albania and the Adriatic Sea, prior to reaching ashore in southern Italy.
First gas sales from TAP to Georgia and Turkey are targeted for late 2018 with first deliveries to Europe expected about one year later in early 2020.
Shareholders in TAP are BP (20%), SOCAR (20%), Snam (20%), Fluxys (19%), Enagás (16%) and Axpo (5%).
Image: Officials at the ceremony that marked start of construction of the pipeline project. Photo: courtesy of Trans Adriatic Pipeline.