LISBON, PORTUGAL - The Portuguese navy thwarted an attack on a local fishing boat by pirates off the coast of Somalia, officials said on Thursday.

Fishermen raised the alarm when five pirates tried to hijack their boat some 100 nautical miles (220 kilometres) to the north of Port Bassasso, Portuguese navy officials said in a statement.

A group of Portuguese officers from the Alvares Cabral vessel arrived on the scene by helicopter accompanied by a Spanish navy plane and arrested the five would-be hijackers, the statement said.

This operation "shows pirates that NATO and its partners are coordinated and ready to prevent pirate attacks in the Gulf of Aden," it added.

The UN's International Maritime Organization's (IMO) says that from January to September of this year, 160 acts of piracy were reported off the coast of Somalia, including 34 hijacked vessels and more than 450 people taken hostage.