The video-game industry on Wednesday changed to adults-only the rating of Grand Theft Auto: San Andreas, a best-selling game in which explicit sexual content can be unlocked with an Internet download.

The decision followed intense pressure from politicians and media watch groups, and retailers reacted swiftly -- Wal-Mart Stores Inc., Target Corp. and Best Buy Co. said they would immediately pull all copies from their store shelves nationwide.

The game's producer, Rockstar Games Inc., said it stopped making the current version and would provide new labels to any retailer willing to keep selling the games, which had been rated M for mature. The company also will offer a downloadable patch to fix the sex issue in PC versions and is working on a new, more secure version, to be rated M.

Rockstar's parent company, New York-based Take Two Interactive Software Inc., also admitted for the first time that the sex scenes had been built into the retail version of that game -- not just the PC version but also those written for Xbox and PlayStation 2 consoles.

Company officials had previously suggested that a modification created by outsiders added the scenes.

Take Two spokesman Jim Ankner said in an interview that the questioned scenes were created by Rockstar programmers. "The editing and finalization of any game is a complicated task, and it's not uncommon for unused and unfinished content to remain on the disc," he said.

In a statement, the president of the Entertainment Software Rating Board said the sex scenes were programmed by Rockstar "to be inaccessible to the player."

But ESRB chief Patricia E. Vance also said the "credibility and utility" of the industry-run board's M rating had been "seriously undermined."

Many retailers sell M-rated games, which "may be suitable for persons ages 17 and older," according to the Entertainment Software Rating Board, but will not sell AO-labeled games at all.

Grand Theft Auto: San Andreas was last year's top console game, selling more than 5.1 million copies in the United States after its October release, according to market analyst NPD Group. Xbox and PC versions were released last month.

Take Two said net sales could drop by more than $50 million this quarter, and it lowered financial expectations for the year to set aside funds for returns of the games.

At a Best Buy store, Elia Akau holds Grand Theft Auto: San Andreas. Best Buy said it was pulling copies of the game.