A GLAMOROUS Nazi spy infiltrated Britain’s military command and obtained top-secret battle plans at a critical moment in World War II.

Marina Lee, a Russian-born ballet dancer, is described in intelligence files released by MI5 this week as “blonde, tall, with a beautiful figure, refined and languid in her behaviour”.

She was also a highly effective Nazi spy, whose penetration of the British command in Norway in 1940 helped to swing a key battle, ensuring a defeat for the Allies in the Norwegian campaign.

The Germans invaded Norway on April 9, 1940. Within days the British launched a counter-attack, aimed at the vital port of Narvik.

By the end of May the German commander at Narvik, Lieutenant-General Eduard Dietl, was isolated, under-supplied and outnumbered by the British under Lieutenant-General Claude Auchinleck. At this point the German Abwehr, the military intelligence organisation, deployed a secret weapon: Marina Lee (sometimes spelt Lie), a stunning 30-year-old ballerina and spy.

She fled Russia in 1917 after her parents were murdered by the Bolsheviks. After settling in Norway, she married an engineer named Einer Andreas Lee, and became head of the School of Ballet in Oslo.

British intelligence suspected her of spreading Soviet propaganda, but around 1935 she was recruited by the Abwehr, and became, in the words of MI5, “a highly valued and experienced German agent”. She spoke six languages and used various names. The British also noted her “passion for telling fortunes by cards”.

By May 1940, Dietl’s garrison of 2,000 soldiers and 2,500 sailors was under attack from 20,000 Allied troops. “Dietl was practically defeated and contemplated crossing the Swedish frontier, where he and the remainder of his troops would have been interned,” according to the MI5 report.

At this crucial stage, German secret service dispatched Lee to British military headquarters “to obtain Auchinleck’s plan of attack”.

How she got this information is not known, although MI5 clearly suspected that her feminine charms played a part – “languid behaviour” may be wartime code for seduction.

“She was very beautiful and she succeeded in obtaining details regarding Auchinleck’s plan … with the information she had obtained (Dietl) was able to adjust his position and defeat Auchinleck.”

The last British and French troops were evacuated from Narvik on June 8; two days later, Norway capitulated.

The Abwehr credited Lee with the change in German fortunes, but her intelligence was not the only factor.

The Germans had achieved air supremacy, and relief forces were rapidly approaching from the south, with Auchinleck’s inexperienced troops unable to delay the advance. By early June the deteriorating situation in France had shifted Allied attention to the Continent.

The British did not discover Lee’s existence until late 1940, when German spies posing as meteorologists were captured by the Royal Navy on an Arctic island. One spy, Hans von Finckenstein, revealed her identity, and the key role that German intelligence believed she had played at Narvik. At least two more captured Germans later confirmed Finckenstein’s revelations.

Lee appears to have been rewarded for her intelligence coup. Within a year she had a German passport and was living in a Madrid hotel in neutral Spain. She was paid 5,000 pesetas a month to glean intelligence from Allied officers.

Marina Lee was last spotted by MI5 at the Ritz Hotel in Madrid in 1948, and for some years afterwards British intelligence wondered what had happened to this “very clever and dangerous woman”.

The last entry in her MI5 file speculates that she might have transferred her allegiance to Soviet intelligence. Despite the fate of her parents, the file says, she had been a friend of Stalin and senior figures in Moscow.

Marina Lee might still represent “a potential threat to security”, noted Mrs DM Quinn of MI5, with arch disapproval of this woman with her languid behaviour and uncertain loyalties: “She is, in fact, just the type to transfer her allegiance once they have had a taste of the game.”