The Dutch navy arrested 20 people off the coast of Somalia who are suspected of being the pirates who kidnapped two South African sailors last month, authorities said Wednesday.

"Thirteen suspected pirates were arrested on Friday and seven suspected pirates yesterday," said Wim de Bruin, a spokesman for the Dutch prosecution. "After the arrest, the prosecutor asked that they be officially placed in detention because there are strong indications these people were involved in the attack on the South African yacht" and the kidnapping of two South Africans, he said.

The two groups were travelling in speedboats and threw their weapons into the water before being arrested, said Marloes Visser, a spokeswoman for the defence ministry. "We will try to see if the two groups were part of a single group," she said.

Amsterdam
Dutch police travelled to the area on Wednesday for a more detailed investigation. The pirates were being held on a supply ship, the Amsterdam, Mr De Bruin said. The Amsterdam operates in the Gulf of Aden as part of NATO's Ocean Shield mission against Somali pirates.

Pirates attacked the South African yacht off the Seychelles on October 26, taking three hostages. The skipper, Peter Eldridge, escaped earlier this month, but two South African nationals remain in the hands of pirates.

A court in the Dutch port city of Rotterdam jailed five Somali pirates in June over an attack on a cargo ship in the Gulf of Aden, the first conviction of its kind in Europe.