Greece is expecting to sign a preliminary agreement for the country’s participation in Russia’s planned extension of a gas pipeline through Greek territory, Greek energy ministry officials said Thursday. Meanwhile, Russian gas giant OAO Gazprom OGZPY 0.18 % said it had reached a preliminary deal with three European energy companies to double the capacity of a gas pipeline that takes Russian gas to Germany under the Baltic Sea. The potential Greek-Russian agreement, which wouldn’t be legally binding, is expected to be signed Friday during Greek Prime Minister Alexis Tsipras’ visit to an economic conference in St. Petersburg. Mr. Tsipras is due to meet Russian President Vladimir Putin Friday on the sidelines of the forum. The agreement on the so-called ’Turkish Stream’ gas pipeline, which would bring Russian gas to Europe through Greece and Turkey, […]