Danish scientists head for the Arctic ice pack on Sunday seeking evidence to position Denmark in a race to claim the potentially vast oil and other resources of the North Pole region. Russia sent two small submarines to plant a tiny national flag under the North Pole last week. Canada, the United States and Norway also have competing claims in the vast Arctic region, where a US study suggests as much as 25 percent of the world's undiscovered oil and gas could be hidden. The monthlong Danish expedition will seek evidence that the Lomonosov Ridge, a 2,000-kilometer- (1,240-mile) underwater mountain range, is attached to the Danish territory of Greenland, making it a geological extension of the Arctic island. That might allow the Nordic nation to stake a claim under a UN treaty that could stretch all the way the North Pole, although Canada and Russia also claim the ridge.