A group of EU member states led by Italy excoriated a German pipeline project with Russia on Friday, tasking the European Commission with probing whether it met Europe's energy rules.

Formally known as Nordstream 2, the pipeline under the Baltic Sea has angered EU diplomats who accuse Germany of selfishly seeking a reliable energy supply route with Vladimir Putin's Russia all while pressuring other countries to back economic sanctions against Moscow over the crisis in Ukraine.

"For the first time, we have an absolute majority of countries that back the Italian position," said Italian Prime Minister Matteo Renzi after an EU summit in Brussels that tackled key topics including energy, migration and terrorism.

Renzi said the Nordstream project, which aims to increase gas delivery capacity to Germany from Russia bypassing Ukraine, was moving forward "in total silence", adding that "when I see a problem, I raise my hand."

Earlier this week Italy led a push to delay rolling over economic sanctions against Russia, amid reports that Rome was frustrated with what it saw as a hypocritical stance by Berlin.

EU President Donald Tusk, who chaired the summit of the 28 leaders, admitted the Nordstream talks were heated.

"It was an emotional discussion," he said.

"Any new infrastructure should be in line with ... all the EU's applicable legislation," he said about the project.

The European Commission, the EU's energy regulator, has said the Nordstream pipeline risks concentrating 80 percent of the European Union’s Russian gas imports on one route and will now look into whether the project meets European laws.

A Commission spokesman said the EU would take a close look at the project and not rush to conclusions on a case this sensitive.

The Commission caused a huge controversy last year when it cancelled a separate Southstream project that would have sent Russian gas through southern Europe, supplying Italy, the EU's third biggest economy.

Tusk said it was important to satisfy "Italy and Bulgaria and other member states ... (and) clarify why Southstream was impossible and Nordstream is possible."

Germany's Chancellor Angela Merkel said that Nordstream was above all a commercial accord concerning companies and not nations, which Renzi dismissed.

"We know that this Nordstream deal has an immense political value," Renzi said.

Kremlin-linked Gazprom announced in early September a shareholders agreement with the German groups BASF and E.ON, France's Engie, Austrian OMV and Anglo-Dutch Shell to begin work on the Nord Stream 2 project.