Norway's oil wealth fund's value jumped 13.4 percent last year.
The jump for the fund is the second largest ever, after it lost 2.6 percent of its value in 2011.
The fund is said to be worth $670 billion now - about 40 percent larger than the entire Norwegian economy, said the BBC.
Surging stock markets around the world are behind the increase in value, said AFP, which also reported that the steep increase was unlikely to be repeated in the coming years.
"The fund's performance reflects development in global financial markets during 2012," the fund's CEO Yngve Slyngstad said, reported the BBC.
Norway's sovereign wealth fund is one of the largest investors in the world and is managed by the country's central government.
AFP reported that the increase was due to a 276 billion kroner transfer into the fund by the government last year.
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