Harper Was Told Nexen Would Give Cnooc Stake in Key Asset

Cnooc Ltd.’s $15.1 billion takeover of Nexen Inc. would give the Chinese company the largest stake of an oil field in the North Sea that “has increasingly influenced” global oil prices, according to a memo sent to Prime Minister Stephen Harper by Canada’s top government worker.

Nexen says it controls 43 percent of the Buzzard oil field in the North Sea, off the coast of Scotland. Buzzard, which began production in 2007, is the largest discovery off the U.K. in the past two decades, according to Nexen’s website.