SAN FRANCISCO – The video game industry yesterday changed to adults-only the rating of “Grand Theft Auto: San Andreas,” a best-selling title in which explicit sexual content can be unlocked with an Internet download.

The decision followed intense pressure from politicians and media watch groups.

Grand Theft Auto’s producer, Rockstar Games, said it was now working on a new version of the game that would satisfy the original “M” for mature rating. It said it would provide new labels to any retailer willing to continue selling the version currently on store shelves.

Rockstar’s parent, Take Two Interactive, also admitted for the first time yesterday that the sex scenes had been built into the retail game – not just the PC version but also those written for Xbox and PlayStation2 consoles.

Company officials had previously suggested that a modification created by outsiders added the scenes to the game, last year’s best seller in consoles.

“There is sex content in the disc,” Take Two spokesman Jim Ankner told The Associated Press. “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.”

The sex scenes, inserted in a game whose main character seeks bloody vengeance on gang-filled streets while picking up scantily clad women, had prompted outrage from parents’ groups and politicians, including Senator Clinton.

While Mrs. Clinton said she was pleased by the move yesterday, she said, “the fact remains that the company gamed the ratings system and enabled pornographic material to get into the hands of children.

“So many parents already feel like they are fighting a battle against violence and sexually explicit material with their hands tied behind their backs,” Mrs. Clinton said in a statement. “We need companies to be responsible and we need rating systems that work.”

The president of the Entertainment Software Rating Board (ESRB) said in a statement that the sex scenes were programmed by Rockstar “to be inaccessible to the player.”

But ESRB chief Patricia Vance also acknowledged that the “credibility and utility” of the industry-run board’s initial “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 rating board, but won’t sell “AO”-labeled games at all.

Take Two also said yesterday that it expects to suffer financially. It lowered its expectations for its current quarter and fiscal year to set aside funds for returns of the games, and figured that net sales could decrease by more than $50 million during the quarter ending July 31.

The rating change was vindication for Patrick Wildenbourg, the Dutch programmer who developed and freely distributed the modification that unlocked the controversial content in the game’s PC version.

Such “mods” are wildly popular in the hardcore gaming community and – authorized or not – exploit the medium’s interactive nature to extend the playing life of many popular titles.

Take Two president Paul Eibeler stressed in a statement that only an unauthorized “mod” makes the sex scenes available, and said “the decision to re-rate a game based on an unauthorized third party modification presents a new challenge for parents, the interactive entertainment industry, and anyone who distributes or consumes digital content.”

That prompted an angry reaction from David Walsh, founder of the National Institute on the Media and the Family,a Minneapolis-based group that monitors the industry.

Mr. Walsh criticized Rockstar for a “carefully worded statement” that leaves the impression that “modders” are responsible for the content. “They did not take responsibility for the fact that this code was created within their company and placed on disks and shipped to responsible retailers.”

The Parents Television Council, another group that monitors sex and violence, said it was pleased with the rating switch but called on Rockstar to voluntarily recall the game and offer refunds to anyone who purchased it.

“I tip my cap to that first step of showing responsibility,” said the council’s executive director, Tim Winter. “Phase two needs to be absolutely getting to the bottom of this coding issue. How did it get into that game? How did it get past the ratings board?”

The ESRB was formed 11 years ago amid congressional pressure to crack down on violent video games. The board now issues ratings for more than 1,000 game titles each year.

Game makers must submit a lengthy form describing the most extreme content and turn over visual samples and scripted dialogue as each game nears the final stages of development.