SHANGHAI — The buying and selling of the make-believe currencies used in online gaming has become so widespread that Chinese authorities fear it will affect the real economy.

To quell that threat, those authorities said on Tuesday that they had issued new regulations aimed at restricting the trade and use of virtual money.

China is one of the world’s biggest markets for huge so-called multiplayer online games like World of Warcraft, and tens of millions of young people are believed to be trading virtual goods and credits for real goods and cash.

The coin of fantasy realms have already moved markets here. So-called QQ coins — a form of currency produced by the Chinese Internet giant Tencent — have sometimes risen sharply in value against China’s official currency, the renminbi, alarming officials at the nation’s Central Bank.

Some people have even traded virtual currencies in China, and exchanged them for clothes, cosmetics and other goods.

Last year, nearly $2 billion in virtual currency was traded in China, according to the China Internet Network Information Center. Some experts say they believe there is a much larger underground economy in the virtual world.

Most of China’s big Internet companies — like Sohu.com, Netease and Tencent — have some gaming component and virtual currencies have grown up alongside many of them.

Some smaller gaming companies have even set up what are called virtual sweatshops, cramped quarters where young people play online games to earn credits that the companies then sell at a profit to overseas customers in Taiwan, South Korea and even the United States.

This practice is popularly known in the online gaming community as gold farming.

Many online marketplaces, like eBay and China’s Taobao, even have online advertisements offering virtual goods for sale, like World of Warcraft gold coins and virtual swords for the game Legend of Swordmen.

Edward Castronova, a professor of telecommunications at Indiana University Bloomington who says he believes virtual currencies could pose a threat to world economies, applauded Beijing’s move.

“This action shows that at least one government is concerned about the way virtual worlds challenge its control of society,” Professor Castronova said in an e-mail message Tuesday. “As virtual currencies take over more and more purchasing power, control over the effective money supply shifts from the central bank to the game developers.”

On Tuesday, China said that new regulations would restrict the trading and use of virtual money, and that virtual currencies would be banned from being exchanged for goods.

The government also said it was moving to fight online gambling and disputes over virtual coins.

In a release, Beijing said that while virtual currencies had helped promote online gaming, they have “also brought new economic and social problems.”

Beijing has repeatedly sought to tame the online gaming market with new regulations (and even Internet addiction camps) but the activity continues to grow.

The new rules, issued jointly last weekend by the Ministry of Commerce and the Ministry of Culture in Beijing, are the government’s strongest effort yet to tame virtual money.

The regulations were widely circulated just as Beijing announced it would delay adoption of a widely criticized plan to install software that was supposed to censor pornographic and other “unhealthy” Web sites in all personal computers sold in China.

Richard Ji, an Internet analyst at Morgan Stanley, released a brief report Tuesday saying he expected only limited financial impact on Chinese gaming companies because much of the trading in virtual currencies and goods does not occur on the sites of big, publicly listed gaming companies, he says; it occurs on other Web sites.