The study -- by France's Capgemini consulting and professional-services firm and Merrill Lynch & Co. -- also found the number of Norwegian millionaires grew 9.7 percent last year.

This is a faster growth rate than the 8.3 percent world average and the 6.4 percent European average, Oslo's Aftenposten daily reported.

Capgemini attributed the large number of Norwegian "dollar-millionaires" to the country's strong economy and a booming Oslo Stock Exchange.

"Most of the new Norwegian dollar-millionaires have earned their money on shares and real estate," Capgemini Nordic financial services industry Director Roger Gullqvist told Norway's Finansavisen financial daily.

Norway's millionaire abundance also reflects the country's economic growth since the 1969 discovery of offshore oil, the study found.

High oil prices have sparked an unprecedented boom in Norway's offshore industry and in the economy in general.