Danish specialist troops seized a merchant ship in the Gulf of Aden Friday, soon after Somali pirates had boarded it and tried to hijack it, the European Union's naval force for the area said.

At the same time, Russian sailors boarded and detained a nearby pirates' skiff. The naval force, EU Navfor, the 25-person crew of the Slovenian-owned merchant vessel, the MV Ariella, was safe.

The ship came under attack early on Friday morning, EU Navfor said in a statement.

"The Ariella was sailing in a 'group Transit' within the International Recognised Transit Corridor under the protection of coalition navies. An alert went out, picked up from an Indian warship, Tabar, who sent out a general message...

"An EU Navfor French maritime patrol aircraft was quickly on the scene and confirmed a sighting of armed pirates on the deck of the Ariella. The [aircraft] made contact with battle watch officers from the NATO Danish warship Absalon..."

The statement said once the Absalon was sure the Ariella's crew was safe, the special forces were sent in, and sailors from the Russian Navy ship, Neustrashimyy, intercepted the skiff.

The naval force urged all shipping sailing through the high-risk zones of the Gulf of Aden, the Somali Basin and the Indian Ocean adopt its recommended security measures. It emphasised that the Ariella had been registered with the force.