A 13-metre (42-foot) sperm whale died Wednesday after washing up on a Belgian beach, the country's Royal Institute of Natural Science said.

The whale, beached near Zeebrugge by the resort of Knokke-Heist, was pronounced dead by experts early afternoon after hours in pain after being washed ashore wounded, according to the institute's Jan Haelters.

Hundreds of concerned locals had congregated hoping to help, but were kept back by police.

"It's so sad to see," said one of those, Jerome Van Mechelen.

Whales washing up on Belgium's around 60-kilometre (40-mile) stretch of North Sea coast are rare, given the shallow waters in a hugely busy shipping lane.

The last two known cases occurred in 2004 and 1994, the institute told national news agency Belga.