A heavy metal music festival in Germany has banned rucksacks and bags from the main grounds this year for security reasons, organisers said.

Wacken Open Air festival spokeswoman Anna Lorenz said that checking rucksacks would slow security checks too much.

Safety concerns have increased at public events across Germany since a suicide bomber blew himself up outside a music festival in Ansbach last month, injuring 15 people.

Festival-goers will be able to take in waist packs, and larger bags are still allowed at camping sites nearby.

The August 4-6 festival, held in a small village north west of Hamburg, is expected to draw 75,000 people this year.

The 120-plus acts include Iron Maiden, Saxon and Blind Guardian.