A helicopter from a Portuguese frigate on Friday thwarted an attack by pirates on a merchant ship off the coast of Somalia, the Portuguese military said.
The frigate, part of NATO's anti-piracy initiative in the Gulf of Aden, spotted an attempt by the pirates to board the boat, Major Luis Bernardino was quoted as saying by the Lusa news agency.
"The pirates fled in a small support boat after the intervention of the helicopter," he added.
On April 24, NATO decided to extend its anti-piracy work off the coast of Somalia. Four vessels from NATO's Standing Naval Maritime Group One have been conducting anti-piracy work and escorting merchant ships, including some carrying food aid for Somalia, since March.
Pirates attacked over 130 merchant ships in the Gulf of Aden last year, according to the International Maritime Bureau.
Attacks increased tenfold in the first three months of 2009 compared to the same period last year.