BEIJING — Chinese authorities tracked down Los Angeles resident Mike Su recently at a networking banquet in Beijing. They forced him to pack his bags, then whisked him to a budget hotel on the edge of the city where they detained him for a week.

Su's crime? On his flight from Los Angeles, the Web site director had the misfortune of sitting near someone alleged to have contracted H1N1 flu.

"I felt like I was going to prison," said Su, 33. "I read the headlines in the news, but I never thought I'd be the guy who gets quarantined."

The detention meant Su didn't get a chance to strike deals in China for his company, Beverly Hills-based Break Media. He never exhibited signs of illness.

In the two months since H1N1 flu first emerged, China continues to wield some of the toughest controls to combat the spread of the recently designated pandemic. Those include denying visas to travelers from countries where the virus is prevalent, screening airline passengers and enforcing quarantines.

While the effectiveness of these measures isn't yet certain, what's clear is that stringent policies are disrupting business and travel. Foreign visitors are postponing or canceling plans to visit China, fearful of getting snared by the flu dragnet.

Today, occupancy rates at Beijing's five-star hotels stand at 48 percent, down 21 percent from a year ago and about 12 percent below expectations, said Guan Jianxin, a tourism industry analyst for Minzu Securities.

"Hotel owners aren't happy about these quarantine measures," Guan said. "The high-end ones will be hit the hardest because they tend to receive the most international guests."

Xu Feng, general manager of Beijing Dragon City, an online travel agency, said he's had 20 cancellations in recent weeks by customers in the U.S., Europe and Australia. "It's getting worse," Feng said. "All we can do is hope it's temporary."

Tourists disembarking from some international flights in China are greeted by masked health officials who scan each passenger with a temperature gun. The process can take hours.

Despite the potential harm to business, China has defended its procedures. The country is still stung by the memory of Severe Acute Respiratory Syndrome, which wreaked havoc on the population and business environment in 2003.

During SARS, China was accused of hiding the severity of the disease and not reacting strongly enough. This time, criticism has been lobbed at Beijing for being too heavy-handed.

Authorities started detaining and quarantining any traveler with a Mexican passport in early May. That has stopped. But they sequestered New Orleans Mayor C. Ray Nagin for five days in Shanghai last week after someone near him in economy class was suspected of carrying the virus.

The Chinese were unapologetic about detaining one of the best-known mayors in the U.S. China, after all, has only 298 confirmed cases compared with the 17,855 in the U.S. as of Friday, and there have been no reported deaths here. That's proof, some here say, that the tough measures are working.

Chinese nationals who return from countries with high numbers of H1N1 cases are also being encouraged to quarantine themselves at home. Some are complying.

According to the Beijing Municipal Health Bureau, authorities have quarantined 1,243 people as of Tuesday. About 1,000 have since been released.

National figures are unavailable.