NEW YORK (AP)SCO Group Inc., a software developer that is seeking royalties from users of the Linux operating system, has been hit by a coordinated computer attack that has made its Web site inaccessible to many visitors for several days.

It’s the second time this year the Linden, Utah, company’s Web site has been the target of such an attack, in which hackers use multiple computers to overwhelm the site with traffic.

SCO spokesman Blake Stowell said the company has notified law enforcement authorities about the latest attack, which has temporarily knocked out the company’s Internet sites in the United States and in the United Kingdom.

“We are taking this very seriously,” Stowell said. The attack will not prevent the company from conducting its business, he added.

SCO, formerly known as Caldera International, was the target of a similar attack in May and said it suspected supporters of the free Linux operating system were to blame.

The latest attack was apparently organized by an “experienced Internet engineer” with ties to the open-source software community, according to an e-mail from Eric S. Raymond, a Linux advocate and president of the Open Source Initiative, a group that promotes free software to corporations.

Raymond, who said he doesn’t know the identity of the perpetrator, said the hacker has agreed to terminate the attack in response to an e-mail Raymond sent Saturday criticizing the attack and calling on the hacker to stop.

“I’m certainly not without sympathy for the person who did this,” Raymond wrote in an e-mail sent to reporters. “Nevertheless … we must never make this mistake again, whether against SCO or any other predator.”

SCO Group has roiled the Linux community since filing a lawsuit against International Business Machines Corp. in March claiming some of SCO’s Unix software code has wrongly been copied into Linux. SCO also is seeking royalties from Linux users.

Shares of SCO Group closed at $14.85, up $1.30, or 9.6 percent, Monday on the Nasdaq Stock Market.