SHANGHAI, Sept. 4 — In recent weeks, Beijing has begun its most concerted global public relations offensive since the outbreak of SARS, the severe acute respiratory syndrome.

Diplomats and government officials are holding news conferences on food and product safety. They are showing contrition in high-level talks with Western officials and offering tours of government safety laboratories to foreign journalists.

But China has also struck back at critics who have called Chinese goods shoddy or dangerous, and highlighted problems with the exports of other nations.

And, in its latest move to respond to a series of recalls and product safety scandals, Beijing introduced a new food and toy recall system last week and announced a “special war” to crack down on poor-quality products and unlicensed manufacturers.

Marshaling an army of inspectors, the government said it had already begun nationwide inspections of farms, groceries, restaurants and manufacturing operations in an effort to root out fake and substandard goods.

Regulators say that in recent months they have broken up scores of counterfeit drug factories, unlicensed toy producers and criminal networks that make everything from fake bird flu medicine and fake Viagra to counterfeit toothpaste.

Beginning last weekend, regulators also said food packages that did not carry a label certifying them as safe were being blocked from export.

“This is a special war to protect the safety and interests of the general public, as well as a war to safeguard the ‘Made in China’ label and the country’s image,” Vice Premier Wu Yi, one of China’s highest-ranking officials, said at a news conference Friday.

Trying to convince the international community of its commitment to product safety after scandals involving everything from tainted pet food ingredients and toxic toothpaste to toys coated with lead paint, the government on Tuesday offered foreign journalists escorted tours of a toy factory and toy testing lab in Guangdong Province, where most of the country’s — and the world’s — toys are produced. The government hoped the tour would demonstrate that new safeguards had been put in place.

The bold actions and tough talk suggest that China is growing increasingly worried about the possibility of trade sanctions or further damage to its international profile heading into 2008, when Beijing is to be the host to the Summer Olympics.

But the government has also shown its resolve to fight back against critics of its booming exports, with Beijing labeling many of them as trade protectionists. Last week, for instance, China blocked imports of American wood packaging material after officials said inspectors had found the batch to be contaminated with “worms and other creatures.”

That was just the latest such move in a year in which Chinese regulators have rejected imports of American meat, Indonesian seafood and other products from the Philippines, South Korea, Germany, France and Spain, saying those countries shipped shoddy or tainted goods.

But experts say regulators here are facing daunting challenges in trying to overhaul a corrupt and ineffective regulatory system that is ill-equipped to control a marketplace teeming with unlicensed operations and entrepreneurs willing to cut corners to make a bigger profit.

“The reality is this is a vast problem, involving hundreds of thousands of factories, which are hard to police,” said Arthur Kroeber, a longtime China watcher and publisher of The China Economic Quarterly.

The government has also begun a campaign aimed at the domestic market.

In recent weeks, Beijing’s largest state-run television network has been broadcasting a special called “Believe in Made in China,” which features interviews with regulators, reports on China’s biggest companies and segments on “foreigners who buy Chinese goods.”

A promotion for one special called it “fighting to save the reputation of Made in China.” And that’s how many in the government have labeled the initiatives.

Still, most of China’s efforts have been aimed at the international community.

“The government is really, really serious, and you will see concrete results by the end of this year,” Kuang Weilin, deputy consul general in New York said at a breakfast briefing for Western and Chinese reporters in Manhattan last Thursday. “Officials will be held accountable for what happens,” he said, speaking of the local officials who often impede the enforcement of national regulations.

Beijing insists the effort is not all talk, and that improvements are already being seen. And while China has long insisted that 99 percent of the country’s exports to the United States, Europe and Japan are safe, the government has at times acknowledged serious problems in product safety. After government investigators found that Chinese companies had exported tainted pet food ingredients and toys coated with lead paint, they closed factories and even detained managers.

But the recalls continue to come, not just from the United States but from a growing number of other countries.

Two weeks ago, for instance, New Zealand said it was investigating reports about what were being called “chemical pajamas,” or Chinese-made clothing that some scientists said contained dangerous levels of formaldehyde.

Late last week, Canada announced it was recalling thousands of pencils made in China because of fears they were coated with too much lead.

But it is food safety that Beijing has made a top priority. The government says it plans to spend $1.1 billion to improve food and drug safety supervision by 2010. The government also said that under the new recall system announced last week producers would be held accountable for products that pose a danger to public safety.

The government even issued a lengthy white paper on food safety last month and said it would begin offering rewards to those who blow the whistle on bad producers.

Regulators have unleashed a flood of new regulations and initiatives in recent months, including a promise to create national standards to govern things like cooking oils and the fillings of baked goods.

And if anyone has doubts about food safety during the Olympics, Beijing said it was already acting: white mice will be used to test most foods served to athletes, and pigs for pork are already being bred organically, in secret locations. Global positioning system, or G.P.S., technology is being employed to track the whereabouts of some animals.

But clearly, there is still work to be done at home as well. When China Daily, the country’s English-language newspaper, recently asked consumers whether they believed most food in China was safe, 41 percent answered no.