The detailed reports sent from occupied Norway by Einar Skinnarland, who has died in Toronto, aged 84, helped prevent the Nazis from developing an atomic bomb.

Mr. Skinnarland's precise scouting allowed a squad to plant explosives in a plant at Vemork, one of the most spectacular acts of sabotage of the Second World War. The attack was portrayed by Hollywood in the 1965 movie The Heroes of Telemark,starring Kirk Douglas, Michael Redgrave and Richard Harris. The action also inspired several film documentaries and countless books. Telemark, which is located in the centre of southern Norway, is one of 19 counties that make up the country.

Mr. Skinnarland was an engineer by training and a patriot by inclination. He joined the Norwegian resistance and became a British agent, operating in his occupied homeland under threat of certain torture and death if captured. His early messages were decoded by the famous cryptographer Leo Marks, who passed them on to Winston Churchill's war cabinet. At first, Mr. Marks was frustrated by what appeared to be coding errors but then he stumbled upon the importance of Mr. Skinnarland's work.

"It was only when I spotted two words tucked away in the last line that I realized which of us was the chronic invalid," Mr. Marks wrote in his bestselling 1998 memoir, Between Silk and Cyanide. "The words were 'heavy water.' They had been distilled by Morse mutilation into 'heaxy woter.' I wondered what heavy water was."

The Norsk Hydro facility at Vemork produced hydrogen for use as ammonia in fertilizer. One of the byproducts was deuterium oxide, known as heavy water, which was believed vital to the preparation of uranium-235 for use in an atomic bomb. The Special Operations Executive (SOE) was desperate to know about Germany's interest in atomic research and summoned their agent to Britain. Of course, they were unable to provide transport. Mr. Skinnarland was introduced to Odd Starheim, a like-minded resistance fighter with a flair for daring. The two got along famously. "It was sabotage at first sight," Mr. Marks wrote.

Along with four other men, the pair used the cover of bad weather to hijack a 545-tonne coastal steamer. Overdue at its next port of call, the authorities assumed the ship had put into an inlet to wait out the storm. Instead, it disappeared across the North Sea and put into Aberdeen, Scotland.

In his debriefing, Mr. Skinnarland's descriptions convinced the SOE that the heavy-water plant and the nearby hydroelectric works were too difficult for the RAF to target and could be destroyed only by sabotage. After a 12-day crash-course, during which he made one practice jump by parachute and learned to operate a suitcase-sized radio transmitter, Mr. Skinnarland flew back to Norway to be dropped onto the Hardangervidda, a mountain plateau north of his native Rjukan valley.

He was followed later by an advance party of four Norwegians code-named Operation Grouse (later Operation Swallow). The group was dropped on a remote mountainside, only to discover they were about 130 kilometres off course. The four -- Jens Poulsson, Knut Haugland, Claus Helberg and Arne Kjelstrup -- gathered their scattered supplies and began an epic, 15-day trek in sub-zero temperatures across hostile terrain. Finally, they made contact with Mr. Skinnarland.

After securing an engineering job in the construction of a new dam, Mr. Skinnarland sent reports detailing activities at the heavy-water facility, including ever-more increased production. London decided to act.

After a series of disasters that involved the loss of two gliders carrying British commandos, a squad of six reinforcements operating under the code name Operation Gunnerside parachuted into the mountains. An attack was set for the evening of Feb. 27, 1943. Wearing British battle dress and equipped with small arms, submachine guns and L-tablets (L for "lethal dose"), nine of the men scaled a 300-metre cliff face and penetrated the Vemork facility. Four planted a demolition charge in a chamber adjacent to the heavy-water section, while five trained their weapons on the guard barracks. The explosion destroyed 3,000 pounds of heavy water, as well as the concentration cells at the plant.

After retreating down the cliff, five of the six Gunnerside men then fled on skis to Sweden, a perilous flight of about 300 kilometres during which they had to evade German patrols and aerial surveillance. It was Mr. Skinnarland's happy duty to report to London details of the damage as reported in the local, pro-fascist newspapers.

The plant resumed production by fall, which Mr. Skinnarland dutifully reported. On Nov. 16, U.S. bombers knocked out a nearby power station. At the end of the month, Mr. Skinnarland learned that the remaining stocks of heavy water and the most vital equipment were to be shipped to Berlin.

Another plan was hatched. The shipment would be most vulnerable when the heavily guarded cargo was transferred by rail car onto a rail ferry across Lake Tinnsjo. One of the team, Mr. Haukelid, planted a timed charge in the forepeak bilge in the early morning hours of Feb. 20, 1944. At 11 a.m., an explosion sent the ferry and its contents to the bottom of the impossibly deep lake.

On VE Day, Mr. Skinnarland, a captain, who was by then living in a tiny hut hidden in a mountainside forest, emerged as the district leader of Home Forces in Rjukan and northern Telemark county. He had received the Distinguished Conduct Medal for his role in aiding the British. Further honours were awarded after the war, including the Medal of Freedom from the United States, the Croix de Guerre avec palme from France, and the Krigskorset med sverd (War Cross with Sword) from his homeland, its highest honour.

Mr. Skinnarland portrayed himself in Kampen om tungtvannet (The Fight Over Heavy Water), a 1948 Norwegian movie. In the Hollywood version, The Heroes of Telemark,he is played by Brook Williams, a minor actor who appeared in several war movies of the period. The part played by Richard Harris was loosely based on Mr. Haukelid. While Heroes was well received by fans of the war-movie genre, most of the men it portrayed dismissed the effort as mere entertainment.

Mr. Skinnarland was trained as an engineer at a technical college in Porsgrunn and at the Royal Norwegian engineering corps' officer school. He immigrated to the United States shortly after the war and worked for more than four decades on heavy construction projects around the world. He moved to Toronto in 1965 to take an executive position with a construction firm.

Among his many projects were the Detroit Dam in Oregon; the massive Bhakra Dam in Punjab, India, which on its completion in 1963 was the fifth-highest dam in the world at 226 metres; and, the Robert Moses Power Dam on the St. Lawrence Seaway. Other projects included consulting work on the Trans-Alaska Pipeline and the offshore oil platforms of Hibernia.

As well, Mr. Skinnarland found himself on the other side of the dam builders when hired as the principal technical and business consultant of the Grand Council of the Crees of Quebec during negotiations over the James Bay Project in the 1970s.

As project manager of the relocation of Fort George, Mr. Skinnarland was responsible for moving a village of 2,373 at the mouth of La Grand Rivière and relocating it to a new site upstream. The village is now known as Chisasibi, which is Cree for "great river."

Mr. Skinnarland suffered a stroke in March, 2001. He died of a brain hemorrhage in Toronto on Dec. 5 after a series of accidental falls. He leaves his wife Trudi (née Gans), who was born in Fairview, Alta.; five adult children; six grandchildren; and, his sister Solveig.

Mr. Skinnarland was uncomfortable in accepting tributes for his wartime actions. Instead, he always noted the heroism shown by those unknown Norwegian civilians who lost their lives while aiding the resistance.

When he travelled to Washington to accept the Medal of Freedom, Mr. Skinnarland told his wife only that he was on a business trip. He did not want his medals displayed and they remain in a safety-deposit box in a Toronto bank.

The room-sized mountain hut which hid Mr. Skinnarland, who is revered in Norway as a war hero, is displayed at a museum in his homeland, as is his uniform. One peculiar souvenir Mr. Skinnarland did keep with him over the years was the vial in which he had carried his cyanide pill in case of capture.

Einar Skinnarland, engineer, soldier, resistance fighter; born Rjukan, Norway, April 27, 1918; died Toronto, Dec. 5, 2002.