People mob a supermarket for salt purchase in Guangzhou in south China's Guangdong province. Residents in a few Chinese cities have gone on a buying spree of iodized salt in the belief that it would ward off radiation pollution. (Wendy/ColorChinaPhoto/ASSOCIATED PRESS)

When fears of radiation spreading from Japan prompted a rush on iodized salt in China, a weekly business newspaper posted the story on its Web site under the headline: “Panic buying in Guangdong, Shenzhen and Dongguan; iodized salt out of stock, nuclear panic in Japan spreads.”

Within minutes, government censors called the Economic Observer’s vice chief editor, Zhang Hong, “and asked us to delete that post immediately,” he said.

In a small act of defiance, Zhang left the story on the site, but he changed the second part of the headline to read: “Salt bureau said the stock is sufficient.”

That March 17 incident is just one example of the daily, even hourly, tussle between editors of China’s state-controlled media and the Communist government’s army of propaganda officials and censors who want to shape every aspect of what Chinese citizens read, see and think.

Normally, the government’s relentless effort to control information plays out behind the scenes.  But an aggressive news Web site called China Digital Times, based out of Berkeley, Calif., and run by Xiao Qiang, a longtime human rights activist, has begun publicly exposing the practice by publishing the official weekly directives and guidelines to the print media from the government’s main censorship organs.

Moreover, several editors and journalists have begun pushing back. Spurred by the growing popular demand for more openness, and with the Internet and microblogs offering more unfettered information, they are testing the boundaries of what is permissible.  Some editors and reporters, in interviews, spoke candidly, albeit cautiously, about how censorship works in practice, and the growing competing pressures they face between a public that wants the truth and the censors who want to manipulate it.

The main censorship organs are the Communist Party’s Central Propaganda Department and the State Council Information Office, among others. Together, the various agencies involved in censorship are known derisively among Chinese journalists as the “Ministry of Truth,” a reference to George Orwell’s novel “Nineteen Eighty-Four,” about a fictitious totalitarian state that controls the population by falsifying history.

Several editors and journalists who were contacted said that they had not seen the specific directives but that the guidelines described by the China Digital Times Web site closely followed what they have been told.

The list of do’s and don’ts opens a window on how the party and government pay close attention to even the most seemingly routine news stories and how they might affect Chinese opinion.

For example, when the Japanese earthquake struck last month, during China’s annual meeting of its two legislative bodies, the news media were instructed to give prominent coverage to the disaster and the role of the Chinese rescuers, but not to neglect the annual legislative forum.

“We must fully propagandize the state of the rescue work that our teams have initiated in Japan. We must closely follow the circumstances of Chinese people and overseas Chinese in Japan,” the March 13 directive read.

“Do not deliberately criticize or champion the actions of the Japanese government, and do not make any comparisons with anti-seismic and rescue efforts in our country,” the directive continued.

On March 4, a directive read: “Do not report on the incident of an exchange student in Norway injuring himself after parachuting from a tower at the Chinese Academy of Science.”

And on March 3 came the intriguing item: “All media are not to hype the salary increase given to the People’s Liberation Army.”

The case of China’s railways minister, Liu Zhijun, who was fired for corruption, has received widespread coverage here. But on March 4, the Propaganda Department sent the instruction: “All media are not to report or hype the news that Liu Zhijun had 18 mistresses.” (Several outlets had reported on the mistresses before the order).

A March 28 directive stated, “Do not report, repost stories, or comment on the execution of a drug trafficker from the Philippines.” And on March 29, when a story circulated online about a plan by Peking University to screen students for “radical thoughts,” the censors wrote, “All Web site authorities are requested to stop these discussions, and quickly water down this topic.”

Several editors and reporters in Beijing and Shanghai said the latest censorship instructions appear more detailed than usual, reflecting, they said, an official nervousness among the ruling elite that uprisings sweeping North Africa and the Middle East might reach China.

Another senior editor for a Beijing-based newspaper, who asked that he and his paper not be identified, agreed. “Overall, compared with last year, it is true the situation this year is very tight,” he said. “Part of the reason is the general international environment. And also next year is an important year for China, too.” Next year, China is due for a leadership change, with President Hu Jintao and Premier Wen Jiabao set to step down from their posts.

Most journalists said they had never actually seen the written directives from the censors. Those are normally passed on only to a newspaper or television station’s top editor, and the rest of the staff receives spoken instructions.

For newspapers, the top editors are routinely asked to attend meetings at the Propaganda Office, where they are given the latest guidelines. If they cannot attend the meeting, a propaganda official will call the editor.

For Web sites, with their faster-moving pace, the censors prefer to use a Chinese instant messaging system called RTX. And some editors said they might receive a simple e-mail with up-to-date instructions.

In both cases, one editor said, the message typically ends with the request: “Please delete.”

Some editors said they see their jobs as a tricky balancing act, between the demands of a public hungry for real news in a competitive market and the aggressive censors who want to control the flow of news.

Hu Xijin is chief editor of the Global Times, a tabloid-size daily in English and Chinese owned by the Communist Party. “I’ve been appointed by them — they can remove me. So they have influence on me,” he said of the paper’s owners. “And the market has some influence on me. I live between them. But the market has a bigger and bigger influence.”

“We’re not as free as the American media,” Hu said. “But we are becoming freer and freer every day.”

Researchers Wang Juan in Shanghai and Liu Liu in Beijing contributed to this report.