A zoo worker in Spain has died after he was struck by an elephant's trunk, knocking his head against the bars of an enclosure, the zoo and local officials said.

The female elephant, which weighs around 4,000kg, hit the 44-year-old with her trunk on Wednesday morning at the Cabarceno Natural Park near the northern city of Santander, the zoo said in a statement.

The man was rushed to hospital where he died from his injuries some three hours later, it added.

At the time staffers were cleaning the elephant stables as part of their daily duties and the elephant was with her calf in the compound.

"We're talking about unpredictable animals," said Javier Lopez Marcano, the tourism minister in the regional government of Cantabria, which owns the zoo.

"The force of the strike was tremendous, of a magnitude that one could not survive," he added.

Police and the zoo said they had opened an investigation. It is the first such incident in the park's 31-year history.

Cabarceno Natural Park is home to almost 120 animal species including wolves, tigers, lions and jaguars which live in large enclosures where one or more species co-exist.

Last year, a 46-year-old keeper was mauled by a 200kg gorilla at Madrid Zoo Aquarium, leaving her with two broken arms and chest and head injuries.