Two Scots have been arrested in a global crackdown on a website used to stage millions of cyberattacks.

The men - both from Lanarkshire - were seized as part of a major UK National Crime Agency operation against one of the world’s most prolific “booter” services, webstresser.

Authorities around the world on Wednesday took down the website, which allowed customers to buy distributed denial of service or DDOS attacks for as little as $15 a month. Such attacks could shut down or slow down any website targeted.

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The website claimed that it offered a service helping firms “stress test” their websites but effectively anybody who wanted could use it to deny internet services to almost any IP address.

Police in England arrested four people and searched an address in Bradford, West Yorkshire - linked to attacks on seven of the UK’s biggest banks last year.

Other arrests were made in Serbia, the Netherlands, Croatia and Hong Kong. The website’s services in Germany were also seized.

Investigators said cybercriminals used the website, to launch more than four million attacks around the globe.

It had more than 136,000 registered users and could be rented by people with little or no technical knowledge to cripple online services offered by government institutions, police forces and banks.

The NCA, which led the probe with Europol, said its officers identified a “criminal infrastructure” in the Netherlands as part of an ongoing campaign against ‘DDOS-for-hire’ services.

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Jo Goodall, a senior investigating officer on the force, said: “A significant criminal website has been shut down and the sophisticated crime group behind it stopped as a result of an international investigation involving law enforcement agencies from 11 countries.

“Cybercrime, by default, is a threat that crosses borders and our response must be one that utilises the close international law enforcement collaboration that is crucial to tackling this threat.

“The arrests made over the past two days show that the internet does not provide bullet-proof anonymity to offenders and we expect to identify further suspects linked to the site in the coming weeks and months as we examine the evidence we have gathered.”

Gert Ras, from the Dutch National Police, said: “By taking down the world’s largest illegal DDOS seller in a worldwide joint law enforcement operation based on NCA intelligence, we have made an unprecedented impact on DDOS cybercrime.

“Not only were the administrators of this illegal service arrested, but also users will now face prosecution and civil liability for caused damage.”

Youtube tutorials explained in simple terms how the site could be used to “kick people offline”.

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A computer novice could simply type in the IP address of any device and simply overload it for a period of seconds, denying service to the user at the other end. A platinum membership allowed users to overload targeted sites or computers for as little as $50 a month with hits lasting an hour and 40 minutes.

Banks and other institutions attacked with sites like webstresser do not always publicise problems. The attacks earlier this year - never acknowledged - may have cost hundreds of thousands of pounds.