The pirates apparently mistook the FGS Spessart for a commercial merchant ship when they targeted it in the Gulf of Aden, between Somalia and Yemen.

The German supply ship pursued the pirate boat, joined by two other ships, a frigate, a helicopter and a plane.

A Nato spokesman said: "Poor judgment by the pirates turned out to be a real opportunity for seven nations representing three task forces to work together and strike a momentous blow for maritime safety and security."

A boarding team discovered several weapons and transferred seven suspected pirates on to another German frigate.

Nato said the suspects will remain on board until a decision is made as to where they will be prosecuted.