China's military is increasingly using scientific research in the Arctic as a way into the region, a Danish intelligence service said on Friday, warning of an intensifying geopolitical rivalry in the north.

Disputes in the Arctic over global warming and access to minerals broke into the open in May when U.S. Secretary Mike Pompeo accused Russia of aggressive behavior in the polar region and said China's actions must be watched closely.

"A great power play is shaping up between Russia, the United States and China, which is increasing the level of tension in the (Arctic) region," the Defense Intelligence Service said in its annual risk assessment report.