Meanwhile, Linux sellers MandrakeSoft and Red Hat--which are not members of the UnitedLinux group--said they had not been contacted about the allegations and did not see them affecting business.
SuSE's response came shortly after SCO on Wednesday announced it would, which is based on UnitedLinux's software, because of concerns about intellectual property.
SCO, a financially struggling company that claims its Unix intellectual property has been illegally incorporated into Linux, also said it had sent letters to about 1,500 of the world's largest corporations warning they could be liable for using Linux.
Thus far, the legal attacks have been limited to IBM, a SCO licensee, which it claimsillegally to improve Linux. Wednesday's move stands to widen the assault to include Linux users and Linux companies, including SCO's own UnitedLinux partners.
SuSE could be the particular focus of SCO's interest when it comes to the alliance of Linux companies. SuSE's Enterprise Server software forms the basis for the UnitedLinux code, which is sold by members under various brand names. The other members include Conectiva and Turbolinux.
Joe Eckert, vice president of corporate communications at Germany-based SuSE, expressed surprise at the attacks. "SCO's actions are...indeed curious. We are not aware, nor has SCO made any specific attempt to make us aware, of any unauthorized code in any SuSE Linux product," Eckert said in a statement. "As a matter of policy, we have diligent processes for ensuring that appropriate licensing arrangements (open source or otherwise) are in place for all code used in our products."
He said that SuSE had asked SCO for clarification, but said the Lindon, Utah-based company had declined to comment.
However, he said, SuSE was not planning to make any changes to its support of the UnitedLinux code base. "The UnitedLinux code base--jointly designed and developed by SuSE Linux, Turbolinux, Conectiva and SCO--will continue to be supported unconditionally by SuSE Linux," Eckert said in the statement. "We will honor all UnitedLinux commitments to our customers and partners, regardless of any actions that SCO may take or even allegations they may make."
Other Linux sellers say they are perplexed by SCO's allegations, which industry analysts have said are designed mainly to encourage another company to quickly acquire SCO.
Red Hat, by far the largest Linux provider, said it had not had any conversations with SCO about the allegations and did not know which code was being questioned. The company said it has a "serious" program of ensuring it does not violate "valid" copyright claims.
Red Hat also indicated that it did not yet see any effect on business from SCO's tactics. "We've seen no indication from enterprise customers that these statements from SCO have been a deterrent from viewing Red Hat as a trusted provider of Linux solutions," the company said in a statement on Thursday.
Gael Duval, co-founder of MandrakeSoft, which develops, said that it was impossible to come to any conclusions in the absence of any details about which Linux code might be infringing SCO's rights. "SCO has been unable so far to unveil the exact parts of the incriminated code, and it doesn't seem they will do publicly, which could mean that they don't feel very confident about their claims," he said. "(There is) nothing concrete yet."
SCO has not given specifics on which code within Linux might infringe on SCO intellectual property, other than to say that lines of "significant copyrighted and trade secret code" had been copied into the Linux kernel and other parts of the operating system.
Chris Sontag, head of the effort to derive more revenue from SCO's intellectual property, said SCO will disclose specifics in court and to credible third parties who sign nondisclosure agreements. He said observers could be shown the evidence in "a couple of weeks".
ZDNet UK's Matthew Broersma reported from London. CNET News.com's Stephen Shankland contributed to this report.