A Norwegian resistance fighter who led a daring raid to sabotage Nazi Germany's atomic bomb program during World War II has been honoured at a London ceremony.

Joachim Roenneberg led a six-man team for Operation Gunnerside, an attack on the Norsk Hydro heavy water production plant in Vermok, Norway.

The operation, in early 1943, destroyed the plant's supplies of heavy water, which the Nazis hoped to use to produce nuclear weapons.

An earlier unsuccessful raid involving British paratroopers resulted in heavy casualties when the gliders carrying the men crashed and the survivors were captured, tortured and executed by the Gestapo.

The Operation Gunnerside raid was dramatised in the Franco-Norwegian film Operation Swallow: The Battle for Heavy Water in 1948, and the later US movie The Heroes of Telemark, starring Kirk Douglas.

Overnight Mr Roenneberg, who was trained in Britain before Operation Gunnerside, was presented with the Union Jack flag at a ceremony in London attended by Norwegian defence minister Anne-Grete Strom-Erichsen.

What is heavy water? Formally called deuterium oxide

Formally called deuterium oxide First produced in 1932

First produced in 1932 Form of water that contains larger than normal amount of hydrogen isotope deuterium

Form of water that contains larger than normal amount of hydrogen isotope deuterium Essentially non-toxic to humans with accidental or intentional poisoning unlikely if consumed

Essentially non-toxic to humans with accidental or intentional poisoning unlikely if consumed Commonly associated with use in nuclear reactors, but is not itself radioactive

Commonly associated with use in nuclear reactors, but is not itself radioactive Used as coolant in nuclear power plants

Used as coolant in nuclear power plants Can be cheap and rapid route to building nuclear weapons

Can be cheap and rapid route to building nuclear weapons Alternatively, heavy water is often used in human metabolic experiments Source: Wikipedia

Norwegian soldiers laid wreaths on the Special Operations Executive (SOE) monument, marking 70 years since the successful mission.

Mr Roenneberg, 93, said it was "amazing" to be presented with the flag and recalled the feeling of importance of the celebrated mission.

"I think it's an amazing thing to stand and hold the flag that was probably on the pole in 1943," Mr Roenneberg said.

"We had the feeling that it must be some very special thing, since the British started planning our trip immediately after they had lost 41 people.

"So it had to be important."

Ms Strom-Erichsen said the ceremony served as both a remembrance of bravery and the strong relations between the United Kingdom and Norway.

"It's for a very important operation during Second World War which if they hadn't succeeded could have been terrible, not only for Norway but for the outcome of the Second World War," Ms Strom-Erichsen said.

"It is of course a remembrance of brave men and women and also the strong ties between UK and Norway."

AFP/ABC