Operators of a pipeline bringing Russian gas to Europe said munitions found near the infrastructure were cleared from the Swedish waters of the Baltic Sea.

Pipeline consortium Nord Stream AG said munitions were discovered during a routine survey of the second string of the pipeline system last week.

More than 100,000 mines were strewn along the sea floor in what was once considered one of the most densely mined waters in the world. During planning phases in the late 2000s, the consortium managing the Nord Stream submarine gas pipeline through the Baltic Sea said many of the mines along the planned route would be detonated in place to make room for the twin pipeline system.

Most of the unexploded munitions were left over from World War II. The consortium said discovering munitions left over in the area was an "unusual find." The Swedish military cleared the munitions discovered near the second leg of the pipeline system.

"The works were safely completed, despite windy conditions in the Baltic Sea," the consortium said. "Line 2, which had been closed at inlet as a precautionary measure, was reopened and resumed gas transportation."

The first leg of the pipeline system, led by Russian natural gas company Gazprom, went into service in 2011. British energy company BP a year after the pipeline went into service said it was considering linking the Nord Stream natural gas pipeline to British ports.

Gazprom Chief Executive Officer Alexei Miller said in July new lines along what he said was the shortest link between northern Russia and the European market are less than five years off.