Norway police on Oct. 14 investigated reports of a drone flying over the Kaarstoe gas plant in southwest Norway on Oct. 13, while in Arctic Norway a Russian-Israeli citizen was arrested when police found two drones in his car.

The Norwegian military Home Guard has been posted at Kaarstoe and other major energy export facilities since authorities boosted security at Norwegian oil and gas installations after the Sept. 26 Nord Stream leaks.

At 2130 local time (1930 GMT) on Oct. 13, the military posted at Kaarstoe reported that they had seen a drone flying in the vicinity of the plant, police official Kjetil Lussand said.

“Police responded to find the drone and find the operator. They did not find them. We have no suspects and no arrests have been made,” Lussand said.

Even before the Nord Stream incidents Norway’s Petroleum Safety Authority (PSA) had warned energy companies to be vigilant for unidentified drones.

In a separate incident, a Russian-Israeli citizen was arrested at the Storskog border crossing between Norway and Russia on Oct. 13 after police found two drones and several data storage units in his car during a routine check.

The man, police said, had been in Norway since Aug. 25 on a tourist visa and was returning to Russia when he was detained. A court on Oct. 14 ruled that he could be detained for an initial two week-period.

“He had large amounts of data, which we are going through now,” said police lawyer Anja Mikkelsen Indbjoer.

Police were checking whether the drones had been flown in areas where they are forbidden, she said. She declined to say whether police suspected the man of espionage.

Norway is now Europe’s largest gas supplier after a sharp reduction in flows from Russia.

In a sign of the state of high alert over energy security, police on Thursday responded to a threat made by telephone against the Nyhamna gas plant, which alongside Kaarstoe and a handful of other Norwegian sites rank among Europe's largest energy export facilities.