The 16-year-old is alleged to be part of internet campaign group Anonymous which masterminded a string of digital assaults on companies that dropped the whistle-blowing website as a customer.
The group is also under investigation by British police in a bid to snare UK-based cyber cells.
A source said: 'We have been aware of the group Anonymous for some months now and have an ongoing investigation into their activities in the UK.
'No arrests have yet been made concerning the recent attacks.'
Anonymous Avenges Wikileaks
The arrest came as it was revealed that WikiLeaks founder Julian Assange, 39, has been transferred to an isolation cell in London's tough Wandsworth Prison - where he has been BARRED from using the internet.
And with little to pass time but watch TV, Assange has complained about the quality of British daytime shows.
Solicitor Mark Stephens described his mood as 'quite chipper' despite being forced to spend his days watching shows like Loose Women and Bargain Hunt.
Mr Stephens said: 'He doesn't have access to a computer, even without an internet connection, or to writing material.
Anonymous Avenges Wikileaks
Comments