Wal-Mart's lawyers have an early holiday message for Web sites that post Black Friday ads ahead of their official release date: Don't do it.

Wal-Mart Stores Inc said on Friday that its lawyers have sent letters to the Web sites, saying publishing the ads before their official November 19 release date violates Wal-Mart's copyrights and other rights.

Such violations can give rise to liabilities and severe legal penalties, said the letter, posted on the bfads.net Web site. To the extent that the methods of acquisition or use include criminal activity, criminal penalties may also apply.

November 19 is just four days before Black Friday, the day after the Thanksgiving Day holiday when shoppers throng to stores looking for deep discounts that retailers use as a lure to get the key holiday sales season off to a strong start.

But more and more of the advertising circulars retailers put out a few days ahead of Black Friday have found their way to Web sites weeks in advance instead.

When that sort of thing happens, it's hard for our customers to tell whether (the ads) are accurate or not, said Gail Lavielle, a spokeswoman for Sears Holdings Corp. We can't vouch for them if we haven't actually placed them.

Wal-Mart has asked these web sites not to post the ads in the past, but the ads have still been posted, said John Simley, a spokesman for the world's largest retailer.

Designers, printers and others all have access to the Black Friday sale information well ahead of time as the circulars are prepared.

We've made notice everywhere in the custody chain of this information that the information is confidential until it is publicly released, Simley said.

Some of the Web sites are asking readers to contact Wal-Mart and urge the company to change its mind.

Remember, if this is allowed to happen with one store, it can happen with them all and in the future no ads will be able to be released early, said a posting on blackfriday.gottadeal.com, which bills itself the Official Black Friday Deal Site. The post includes a link to Wal-Mart's online feedback page and also has the Wal-Mart media relations telephone number.

While Wal-Mart has attracted attention with the letter to Web site operators, other retailers expressed concern about the early Internet ads but have not moved to crack down on them.

We're not going to spend our time trying to track down all those sites, said Brian Lucas, a spokesman for consumer electronics retailer Best Buy Co. Our focus is so much on trying to execute Black Friday well that we don't really want to be distracted from that.

Many other retailers are also protective of their own advertising materials.

We encourage consumers to consult and rely on the Circuit City ads that actually appear in newspapers nationwide on Thanksgiving, Jackie Foreman, a spokeswoman for Circuit City Stores Inc, said. We do not confirm or deny content that appears on the Internet other than information on our own site.