NAIROBI, April 26 (Xinhua) -- The European Union Naval Force has seized two Somali pirate boats and yet prevented another pirate group from leaving the Somali coast.

Naval Force said the Dutch warship HNLMS Johan de Witt's weekend seizure was the second event in four days of patrolling in the most dangerous waters of the Somali coast.

"After four days of counter piracy operations, this is the second pirate boat, so called whalers, on her flight deck. A good start for a patrol that was slightly different from others," Major Theo Mestrini said in a statement.

Mestrini said the EU Naval Force spotted a whaler, near the Somali coast which was very close to one of the pirate camps where they had seen activities on Friday night.

"After Commanding Officer approval, we approached the whaler. The crew was totally surprised and looked confused. Soon it was clear that this whaler was equipped to be used for pirating. They were ready to set sail to the ocean, but we prevented it," he said.

He said the incident was the second event in four days of patrolling in the area where two whalers were lifted on board of Johan de Witt and 5 crew members of the whaler were sent safely back to the shore.

HNLMS Johan de Witt is the newest and biggest ship of the Royal Netherlands Navy. She can operate near the coast, greatly enhancing EU Naval Force's new strategy.

"It's a new concept and to be honest, the ship was not designed for it. But it shows the flexibility of the ship, the craft and, of course, her crew; they are the ones that do the job," Commanding Officer Ben Bekkering said.

The incident came barely a week after the Somali pirates hijacked three Thai vessels almost 600 miles outside the normal operation area for the EU Naval Force.

The Somali pirates have expanded their range south and east in response to an increase in patrols by European and American warships off the Somali shore.

This was the second event in four days of patrolling in the area. Two whalers were lifted on board of Johan de Witt and five crew members of the whaler were sent safely back to the shore.

The Horn of Africa nation is at the entrance to the Gulf of Aden, which leads to the Red Sea and the Suez Canal, one of the world's most important shipping channels.

The country has been plagued by factional fighting between warlords and hasn't had a functioning central administration since the 1991 ouster of former dictator Mohammed Siad Barre.

The Gulf of Aden, off the northern coast of Somalia, has the highest risk of piracy in the world. About 25,000 ships use the channel south of Yemen, between the Red Sea and the Arabian Sea.