AN 18-year-old man suspected of being one of the leaders of an international group responsible for hacking law enforcement agencies has been arrested in Scotland.

The target went by the online nickname Topiary, is said to be second in command of Lulz Security (LulzSec), and presents himself as a spokesman for the group.

Scotland Yard confirmed that a teenager was apprehended in the Shetland Islands as part of an international investigation into hacking groups Anonymous and its splinter group LulzSec.

Police are also searching a house in Lincolnshire and interviewing a 17-year-old male under caution in connection with the inquiry.

Officers from the Metropolitan Police's e-crime unit arrested the 18-year-old at a house in Shetland.

The swoop is linked to an ongoing investigation into hacking and distributed denial of service attacks, where websites are flooded with traffic to make them crash, against international companies and intelligence agencies.

The suspect was being transported to a central London police station while detectives searched the property in Shetland.

The arrest comes a week after Scotland Yard announced the arrest of LulzSec member Tflow, the fourth founding member of the group. A 16-year-old was arrested in south London on charges of violating the Computer Misuse Act as part of an operation involving the arrest of several other hackers affiliated with Anonymous in the US and UK. He faces extradition to the US.

LulzSec denied that any of its membership had been arrested, stating "there are six of us, and we're all still here".

Scotland Yard's cyber crime unit then acted in co–operation with the FBI, which arrested 14 people for allegedly mounting a cyber attack on PayPal, the online payments company. Dutch police also made four arrests.

A statement from Anonymous and LulzSec attributed to another splinter group AntiSec, yesterday expressed "outrage" at the FBI's "willingness to arrest and threaten those who are involved in ethical, modern cyber operations" while condemning Paypal for withdrawing funds from Wikileaks.

"Quite simply, we, the people, are disgusted with these injustices. We will not sit down and let ourselves be trampled upon by any corporation or government. We are not scared of you, and that is something for you to be scared of. We are not the terrorists here: you are," the statement said.

In concludes: "Anonymous has become a powerful channel of information, and unlike the governments of the world, we are here to fight for you. Always."

Anonymous targeted PayPal's website in retaliation for it withdrawing services from WikiLeaks after the group released thousands of classified US State Department cables last November. Hackers bombarded PayPal with traffic in an attempt to overwhelm its servers and force it offline. The FBI arrests were the first in the US since the international investigation of the group of so-called "hacktivists" began last year.

Topiary manages the group's public image, its Twitter feed, which has received nearly 350,000 followers, and is key to all the hacktivists' public statements.

He is a self-described "Supporter of Anonymous Operations, WikiLeaks, and maintaining freedom on the Internet" and has also said he was a "simple prankster" who has "worked with Anonymous, LulzSec and other such paragons of intense cyber victory".

LulzSec emerged in May this year and targets have included the UK's Serious Organised Crime Agency, the US Senate, the CIA, Fox News, the US Public Broadcasting Service and the FBI.

More recently LulSec has claimed responsibility jointly with Anonymous for infiltrating the website of The Sun newspaper, redirecting users to a spoof Sun online article claiming that Rupert Murdoch had been found dead.

Topiary's Twitter account, was all but wiped yesterday. The only remaining entry, posted on July 22, three days after The Sun attack said: "You cannot arrest an idea." In one of its latest Twitter messages, LulzSec said it was working with unnamed media outlets on a WikiLeaks-style release of emails it claimed to have stolen from the tabloid.

Topiary was identified in one television interview on US news talk programme, the David Pakman Show, earlier this year. Topiary phoned via Skype to feud with Shirley Phelps-Roper of the Westboro Baptist Church, a Kansas-based group notorious for picketing the funerals of slain American soldiers.

Anonymous vandalised the church's website over the course of the interview.

One of its most spectacular hacks was against Sony Pictures in June.