The German naval frigate Hessen, deployed to Red Sea as part of an EU naval mission to protect shipping, has repelled an attack by the Iran-backed Houthi militia in Yemen for the first time, according to dpa sources.

The vessel successfully engaged two enemy targets on Tuesday evening, sources said.

This was the German navy's first live weapons engagement of the deployment, which began on Friday and is considered one of the German armed forces' most dangerous missions in decades.

The mission is about protecting international law, freedom and security on the seas, but also about stabilizing trade routes and the entire region, German Defence Minister Boris Pistorius said last week.

Houthi militants from Yemen have been attacking ships in the Red Sea in what they say is retaliation for Israeli military action in the Gaza Strip.

EU foreign ministers approved the mission, called Aspides after the Greek word for "shields," on Monday. It involves sending European warships and airborne early warning systems to the Red Sea, the Gulf of Aden and surrounding waters.

Aspides vessels have orders only to fire on the militants if they attack first and are be authorized to shoot pre-emptively. The operational command is in the Greek city of Larissa.