Two German boys have died after being buried at the weekend by a dune landslide at a beach in Denmark, police said Wednesday.

The children, aged nine and 12, were digging a hole on a beach in North Jutland on Sunday when the dune collapsed, burying them.

Police said health authorities reported the boys died Tuesday evening, adding that they considered the incident a "tragic accident."

Media reports said the boys, who were on holiday with their families from the Munich area, were trapped under the sand for up to 40 minutes during efforts to dig them out.

In a separate incident on Sunday, another young boy got caught in a dune landslide in southwestern Jutland, but he was pulled out quickly and unharmed.

Following the incidents, Danish authorities urged people to exercise caution around dune areas on the west coast as recent heavy rains had made the dunes unstable.