Norwegian media have named a DNV GL employee accused of passing state secrets to Russia.

Norwegian citizen Harsharn Singh Tathgar, 50, denies endangering national security after being arrested following a meeting with a Russian intelligence agent in an Oslo restaurant on Saturday.

TV 2 said the Indian-born executive has been active in the Liberal Party's local party Vestre Aker, but has not played a central role.

He was on the electoral list for the city council last year, but was not elected.

Tathgar himself has demanded his release from four weeks of custody imposed by a local court as the probe continues.

"What I can say is that he does not admit criminal guilt. He has explained himself and is willing to explain himself further to the police," said Tathgar's lawyer Marianne Darre-Naess.

Norwegian media said he has told police he handed over information and received money for this.

"The accusation is based on the fact that there have been meetings between the accused and a Russian intelligence officer," said Norwegian security police attorney Line Nyvoll Nygaard.

"Reference is made to the hidden meeting activities over time, the way they have communicated, and to the fact that he has received not insignificant amounts of cash in return," the Oslo district court wrote.

DNV GL confirmed the accused had been employed at the classification society for several years, working in the defence sector.

The company is cooperating with the authorities. "We’ll be working closely with the police to assist in their investigation," it said.

"This is an extremely serious case and we need to get to the bottom of it.

This story first appeared in Upstream's sister publication TradeWinds.