This photo released by the French Navy shows pirates holding their hands up to soldiers, left, of the French vessel La Somme, early Wednesday Oct.7, 2009 off the Somalia coast. Somali pirates in two skiffs fired on a French navy vessel early Wednesday after apparently mistaking it for a commercial boat, the French military said. The French ship gave chase and captured five suspected pirates.(AP Photo/Olivier Amalvict/ECPAD/French Navy) ** NO SALES

The Hague -

Dutch sailors taking part in NATO's piracy-busting operation Ocean Shield on Thursday detained seven suspected pirates off the coast of Somalia after an attack on a Spanish vessel.

The alleged pirates were intercepted by Dutch amphibian transport HMS Rotterdam after the Izurdia was ambushed by a skiff off the Horn of Africa, the Dutch defence ministry said in a statement.

“The suspected skiff was stopped after warning shots were fired and a helicopter-borne team boarded the boat,” the Rotterdam's commander Huub Hulsker said in the statement.

“The boarding team detained seven suspects who were taken on board the Rotterdam,” he added.

Details around the attack were not immediately known and a Dutch Defence Ministry spokesman could not immediately be reached for comment.

The 12,700 tonne Rotterdam sailed to Aden on July 11 to take part in Operation Ocean Shield, the defence ministry added on its website.

Statistics from the European Union Naval Force's anti-piracy operation Atalanta say that after a spike last year successful pirate attacks on commercial vessels off the Horn of Africa have diminished.

In 2011 some 151 attacks were recorded, while only 29 took place so far this year, it said on its website.

Pirates currently control six ships and hold hostage an estimated 156 crew members. More than 1,000 alleged pirates are awaiting trial or have been sentenced in 20 countries. - Sapa-AFP