"Spam" e-mail, already a costly and frustrating bane of computer users and corporations, has surged as spammers invoke the war in Iraq as a way to lure customers.

Government regulators and anti-spam software vendors warn of a fresh raft of come-ons that play on emotions and fears about the war, from offering encouragement to U.S. troops to selling patriotic T-shirts, pins and books on how to survive a biological attack. Many are run by known spammers, including some who also are linked to Web sites that offer pornography.

San Francisco-based Brightmail Inc., a major provider of corporate spam-blocking services, estimates it has captured 50,000 different war-related spam messages in its filters since the war began last month. SurfControl PLC, another filtering vendor, said spam has increased by 10 percent in the same period.

An examination of several pieces of war-related spam shows that some lead with subject lines that say "Support Bush & War Effort" but have messages that peddle vacation packages or investment tips.

Others sell products with the promise that a portion of the proceeds will go to support families of soldiers or victims of terrorism.

At www.helpoursoldiers.com, a Web site adorned with images of the American flag, prospective buyers are promised that for every "Pro-American Operation Iraqi Freedom" T-shirt sold, the company will donate money to America First Inc., a licensed Southern California charity dedicated to helping families of the Sept. 11, 2001, terrorism attacks.

The charity's executive director, retired Army Maj. Arthur S. Manchester, said he was not aware of the offer and had received no donations. And when customers decide to purchase a shirt, the electronic payment system used by the site directs funds to Mystro Enterprises Inc., which is separately linked to at least one Internet pornography site. Calls to a Minneapolis company that hosts the T-shirt site were not returned. The pornography site is registered in Antigua.

Another message, with a subject line that says "Support USA Tops 2003," directs potential customers to www.iraqtshirts.com, which is also decorated with stars and stripes and which provides an audio rendition of "America the Beautiful."

The site is registered to Internet Products Group Inc. in Los Angeles, which is identified by bulk-mail tracking organizations as a large spammer marketing various products. A call to the company was not returned.

"We see spam mirroring current world conditions," said S. Brian Huseman, a staff lawyer at the Federal Trade Commission, which maintains a spam database that is receiving roughly 120,000 spam e-mails a day. "In bad economic times, there often are deceptive business opportunities. After September 11, spam tried to promote a sense of patriotism," which the agency is seeing again.

Huseman said that last month the agency logged nearly 2,500 war-related pieces of spam.

As with many marketing offers that are made during times of crisis or disaster, consumer fraud and spam experts warn consumers to be cautious with e-mail solicitations that invoke the war.

"It's human nature, and part of the commercial cycle, that marketers jump on the next bandwagon," said Susan Getgood, senior vice president for marketing at SurfControl. "The key thing is that consumers need to have a certain amount of skepticism."

Particularly insidious, experts say, are e-mails that purport to be surveys measuring public opinion on the war, or that simply offer computer users a way to express their support for the troops.

Responding to these messages is likely to help spammers "harvest" valid e-mail addresses, which are added to lists and sold throughout the bulk e-mail community.

Many of the captured e-mails advertised products leveraging people's anxiety about terrorism and the country's heightened national security alerts.

One message, from a company based in France called BizzyDays Ebook Publications, advertises a downloadable, electronic book that teaches how to survive in the event of a chemical or biological attack.

"You can NOT rely on the authorities to protect your family against attack," warns the site. "Take action now to ensure your family's safety. If YOU don't, who will?"

The book sells for $17, with $1 of the proceeds promised to be donated to "an international aid agency."

The author is listed as Nathalie Hopkins, whose credentials are not provided. The company's contact name is listed as Michael Hopkins. A call to the listed telephone number in France was not answered.

The BizzyDays site lists many other e-books and articles for sale, including titles on healthy baby food, how to increase traffic to Web sites, and how to get marketing e-mail past electronic spam filters.