To the consternation of marketers and the delight of consumer groups, government officials in China are cracking down on advertising claims.

For years, multinational advertisers had a fairly free hand in China, where regulatory oversight has been less stringent than in developed markets.

But recent government actions against consumer-products giant Procter & Gamble Co. indicate a stricter approach.

Television commercials and packaging for four of the Cincinnati-based company's household products, including Pantene shampoo, were banned or placed under investigation last month by authorities in Zhejiang province and Beijing after the company failed to cite the source of its claims -- that Pantene makes hair 10 times stronger, for instance.

P&G stands behind the claims, as do its advertising agencies, including WPP Group's Grey Worldwide in China, the ad agency that produced the Pantene commercial.

"Everything we put on the air is researched and it's true," said Daisy Ching, P&G's brand manager at Grey.

Wang Gang, a Zhejiang official, said an investigation continues and may include a visit to P&G's offices in Guangzhou.

Consumers -- and the groups that zealously protect their interests -- are slowly becoming a force to reckon with in China. In April, P&G paid a $24,000 fine to the Administration of Industry and Commerce in Nanchang after Lu Ping, an insurance agent there, complained that the company's $100 SK-II skin cream wasn't the "miracle water" it claimed to be. Lu said the product not only failed to make her skin look 12 years younger in 28 days, as its brochures suggested it would, but also caused itchiness and pain.

"I will never believe in any ads anymore," Lu said.

After a flurry of bad press and inquiries by local officials, P&G withdrew cosmetics-counter brochures carrying the claim. P&G acknowledged the "12 years younger" claim came from the best of its results, and was "an incomplete representation of facts."

The two cases have sent shock waves through China's booming ad industry as authorities start to vigorously enforce a 1995 law that stipulates statistical claims and quotations "should be true and accurate, with the sources clearly indicated." In April, 11 ministries and committees of the central government joined forces to launch a crackdown on "false and illegal ads," with a focus on cosmetic, beauty, health and pharmaceutical products. That category of advertising accounted for about a quarter of all ad spending in China last year, figures from Nielsen Media Research show.

An official at the State Administration of Industry and Commerce, calling the problem "severe," said the crackdown was "one of the most important works the State Council will implement this year."

Such ambitious government campaigns in China often go in fits and starts. But in going after a company as large and well-established as P&G, officials are sending a message to the personal-care industry, said Darren Yao, a senior planner at Omnicom Group's TBWA ad agency. "The government punishing P&G can be a very symbolic warning to all the other companies in this industry," he said.

Unaccustomed to such scrutiny in China, advertisers nevertheless are resigned to the change -- the market is too big and promising to quit. P&G, an early entrant after the country opened to foreign business in the 1980s, today counts China as its sixth-largest market.

Geoffrey A. Fowler, Ivy Zhang and Sarah Ellison contributed to this report.

Chinese officials are questioning TV ads asserting that Pantene can make hair 10 times stronger.