A member of a hacker collective claimed credit on Monday for downing the web hosting firm GoDaddy, which manages millions of websites around the world.
Credit was claimed on Twitter by AnonymousOwn3r, identified as the "security leader" of the loosely organised hacker group knows as Anonymous.
"Hello http://godaddy.com/ now yes! all servers #tangodown by @AnonymousOwn3r," a tweet said, using the code word for a hack attack.
When some news sites blamed the attack on Anonymous, the same individual responded on Twitter by saying: "it is not Anonymous coletive (sic) it's only me don't use Anonymous coletive name on it, just my name."
GoDaddy issued its own statement on Twitter: "Status Alert: Hey, all. We're aware of the trouble people are having with our site. We're working on it."
The company added later: "So many messages, can't get to you all... Sorry to hear all your frustration. We're working feverishly to resolve as soon as possible."
The purported hacker, when asked about his motivation, tweeted; "I'm taking godaddy down bacause well i'd like to test how the cyber security is safe and for more reasons that i can not talk now."
Another message said the attack had no specific time frame: "it can last one hour or one month," the tweet said.