WASHINGTON -- One of the country's main monitors of hate groups asked Congress Friday to investigate possible racial extremism in the military, after finding U.S. service members participating on a social networking site advertised as being for white people only.

Researchers from the Southern Poverty Law Center, based in Montgomery, Ala., identified about 40 personal profiles of people who list the military as their occupation on the Web site New Saxon, according to the group's founder, Morris Dees.

The site, run by the Detroit-based National Socialist Movement, describes itself as an "online community for whites by whites." He said some of the participants are wearing military uniforms in profile photos, although it was not possible to verify whether any of them are actually serving in the armed forces.

Examples that Dees cited from the Web page include:

--A person claiming to be in Iraq, who writes that he "hate(s) illegal immigrants with a passion and feel(s) every true red-blooded, white American should do whatever it takes to stop the foreign invasion."

--One who said he was serving in Afghanistan lists as his favorite book, "The Turner Diaries." The novel is a favorite of white supremacists.

"We urge your committees to investigate the threat posed by racial extremists who may be serving in the military to ensure that our armed forces are not inadvertently training future domestic terrorists," Dees wrote in a letter addressed to four congressional committee chairmen.

Dees said existing Pentagon regulations that prohibit active participation in extremists groups should be strengthened further.

Lt. Col. Les' A. Melnyk, a Pentagon spokesman, said in an e-mail that current policy is believed to be sufficient. Under it, military personnel "must reject" participation in organizations that espouse supremacist causes.

"We believe the policy ... is broad and inclusive in its definition of 'active participation,' and encourages commanders to pursue and weed out service members who actively participate in these types of groups," Melnyk said.

Jeff Schoep, commander of the National Socialist Movement, said there are members of the military who participate on the site, but not all are members of his organization. He could not say how many there are.

When violent material is found on the site, Schoep said, it is removed and the offender faces losing future privileges.

He said there are more "racialists" in the military now, but those who are members of his organization are advised not to recruit others.

"If they just mind their P's and Q's in there, and are good soldiers and do their jobs, then they have every right to be there just like anybody else," Schoep said.

Julie Ziegenhorn, a Pentagon spokeswoman, said in an e-mail that as a matter of policy the Department of Defense doesn't block or prohibit access to Web sites on the basis of content. But she said commanders in the field have the option to block access on governmeny computers to sites they deem inappropriate.