Spain, Portugal, and France said on Thursday they will build a sea-based pipeline to carry hydrogen and natural gas between Barcelona and Marseille, substituting plans to extend the so-called MidCat pipeline across the Pyrenees that France opposed, Reuters reported.

The route, dubbed BarMar, will mainly be used to pump green hydrogen and other renewable gases but will also temporarily allow for the transportation of a "limited amount" of natural gas to help alleviate Europe's energy crisis, Portuguese Prime Minister Antonio Costa said.

The pipeline "is a response to calls for solidarity from our European partners in the face of [Russian President Vladimir] Putin's blackmail," Spanish Prime Minister Pedro Sanchez told reporters in Brussels, where the three leaders met on Thursday.

French President Emmanuel Macron said it was "imperative that Europe remains united."

The BarMar resolves a stand-off between Spain and Portugal, which wanted to extend the MidCat pipeline so that they could sell natural gas to central Europe, and France, which argued that the pipeline would take too long to build to resolve short-term supply issues.

"It's good news, one of Europe's oldest blockades has been overcome," Costa said.

Spain and France also agreed to speed up an electricity interconnection through the Bay of Biscay and identify and work on other connections between the two national grids, according to a joint statement.

The leaders of the three countries agreed to meet again in Alicante, Spain, on December 9 to decide on a construction timeline and how it will be financed.