[Shaun]

Norway's world swimming champion Alexander Dale Oen, has died suddenly in the US, aged 26, the country's swimming federation says.

In July 2011, Dale Oen won gold medal in the 100m breast-stroke at the Fina World Championships in Shanghai.

He was found collapsed in a shower late on Monday after training in Flagstaff, Arizona, Norwegian media say. Friends said he had appeared healthy earlier.

Emergency services arrived within minutes but were unable to revive him.

Norwegian Swimming Federation President Per Rune Eknes said he had suffered a cardiac arrest.

Oen's last tweet on Monday, as he was coming to the end of training in the US, said "2 days left of our camp up here in Flagstaff, then its back to the most beautiful city in Norway #Bergen".

Oen won a silver medal in the 2008 Olympics in Beijing and was considered a strong hope for this summer's London Games.

His gold medal in Shanghai came shortly after Anders Behring Breivik murdered 77 people in Oslo and the island of Utoeya and at the time he described the events at home as a motivation for him. "We can't let this guy ruin the future for us," he said.

So sad