Greece's frigate Hydra departed for the Red Sea on Monday to participate in a mission to protect merchant ships from attacks by Yemen's Iran-backed Houthi militia, a defence ministry official said.
Earlier on Monday, the Greek government approved the country's participation in the European Union naval mission dubbed Eunavfor Aspides in the Red Sea.
Many commercial shippers have diverted vessels following attacks by the Houthis who control much of Yemen and say they are acting in solidarity with the Palestinians as Israel and Hamas wage war in Gaza.
Greece's security council approved a proposal by Defence Minister Nikos Dendias for participation in the EU mission, government spokesman Pavlos Marinakis said in a statement.
The government said it was important to join the mission as the Houthi attacks have disrupted Greek-owned commercial vessels' activities at the country's biggest port Piraeus and some container ships have stopped using it.
France, Italy and Germany are also taking part in the EU mission, under the code name "Aspides", the Greek word for shields.
Participating countries will be mandated to protect commercial ships and intercept attacks, but not take part in strikes against the Houthis on land.
Several Greek-owned merchant ships have been hit off Yemen since November, suffering damages but no casualties.
Reporting by Lefteris Papadimas