Dutch police have arrested a 16-year-old who has admitted to staging cyber attacks on opponents of whistleblower website WikiLeaks, the national prosecutor said.

Wim de Bruin, the spokesman for the national prosecutor's office, said the teenager had "admitted launching attacks on Visa and Mastercard sites."

A statement said he was "probably part of a larger group of hackers," a statement said.

The teenager will appear before a judge on Friday in Rotterdam.

The attacks came after the arrest of WikiLeaks boss Julian Assange, currently in a British jail, as Sweden seeks his extradition on rape charges.

Hackers - dubbed "hack-tivists" - stepped up cyber attacks on those they perceived as opponents of WikiLeaks, including companies who in recent days have deprived the organisation of their services.

But after taking down the websites of Visa, Mastercard and others, supporters of the whistleblower website tried, but failed, to knock online retail giant Amazon.com offline.

WikiLeaks distanced itself from the cyber attacks but said it was a reflection of public opinion.

"WikiLeaks is aware that several government agencies and corporations, including the Swedish prosecutor, Mastercard, PayPal and State.gov [US state department] have come under cyber attack in recent days, and have often been driven offline as a result," a WikiLeaks statement said.

"The attacks are of a similar nature to those received - and endured - by the WikiLeaks website over the past week, since the publication of the first of 250,000 US embassy cables.

"These denial-of-service attacks are believed to have originated from an internet gathering known as Anonymous.

"This group is not affiliated with WikiLeaks. There has been no contact between any WikiLeaks staffer and anyone at Anonymous. WikiLeaks has not received any prior notice of any of Anonymous's actions," the statement added.

One Anonymous member, who goes by the name Cold Blood, says they are fighting a war for the freedom of information.

"We're trying to keep the internet open and free to everyone," he said.

"Just the way the internet has been ... but in recent months and years we've slowly seen governments, the European Union, slowly try and creep in and try and limit the freedom that we have on the internet."

- AFP/BBC