FBI agents executed more than 40 search warrants on Thursday in the United States to investigate cyber attacks against businesses and organizations. The searches are apparently connected to hackers who acted in sympathy to WikiLeaks.

Among the corporate websites targeted in the cyber attacks were those of PayPal, Visa and MasterCard after the companies cut their service with WikiLeaks, once it started publishing leaked classified cables, according to a report from TechZone360.

In a related matter, the United Kingdom’s Metropolitan Police Service executed search warrants in England and arrested five people for their role in cyber attacks. U.K. authorities say the five males, who are ages 15, 16, 19, 20 and 26, were in custody after coordinated arrests at residences in the West Midlands, Northants, Herts, Surrey and London, England.

The investigations focus on distributed denial of service attacks (DDoS), the FBI said.

These occur by using software which “damages a computer network’s ability to function by flooding it with useless commands and information, thus denying service to legitimate users,” according to a statement released by the FBI.

A loosely organized group, which goes by the name   “Anonymous,” claimed responsibility for the attacks, the FBI said.

The group said the cyber attacks were a form of “protest of the companies’ and organizations’ actions,” according to the FBI.

The FBI explains that facilitating or executing a DDoS attack is illegal in the United States. If convicted, a defendant may be sentenced to as much as 10 years in prison, as well as having potential civil liability in a lawsuit.

Governments in the Netherlands, Germany and France started their own investigations into the DDoS attacks, the FBI said.

In December, a 16-year-old Dutch boy was arrested by Dutch police for his alleged role in attacks on MasterCard and Visa websites, after they cut off services to the embattled WikiLeaks’ site, according to TechZone360.

The National Cyber-Forensics and Training Alliance (NCFTA) is assisting law enforcement agencies in their investigations.

In addition, several software providers have released software updates to detect “Low Orbit Ion Canon” tools that apparently were used in the cyber attacks, according to the FBI.

WikiLeaks has been the focus of public controversy after it began publishing classified diplomatic cables. The content of the cables embarrassed world leaders and put U.S. policies and the lives of operatives at risk, several political leaders have claimed.