BEIJING - Beijing will permit public protests inside three designated city parks during next month's Olympic Games, but demonstrators must first obtain permits from local police and also abide by Chinese laws that usually make it nearly impossible to legally picket over politically charged issues, the authorities announced Wednesday.

The arrangement marks a break from normal practice in China's authoritarian political system and seems loosely modeled on the protest zones created at previous Olympic Games and at many recent international political gatherings that attract large numbers of protesters.

It remained unclear whether international advocacy groups on issues such as Tibet, Darfur and broader human rights would be able to secure the bureaucratic approvals needed to use the protest zones and whether they would be arrested if they held demonstrations elsewhere in Beijing.

With only 16 days until the Olympic opening ceremony, China's ruling Communist Party is tightening security across the country and has shown little appetite for domestic political dissent. Several dissidents have been jailed, monitored or placed under house arrest in recent months.

Liu Shaowu, director of security for Beijing's Olympics organizing committee, said that Ritan Park, Beijing World Park and Purple Bamboo Park would be designated for protesters during the Games and that the approval process would be regulated by Beijing's public security bureau.

"The police will safeguard the right to demonstrate as long as protesters have obtained prior approval and are in accordance with the law," Liu said during a news conference.

The issue of how much space, if any, China would allow for legal demonstrations became especially charged after the international Olympic torch relay earlier this year was marred by violent protests in London and Paris during angry confrontations between pro-China supporters and advocates for Tibet. Chinese leaders want the Games to showcase the country's achievements and are wary of protests being broadcast to a worldwide audience.

Under Chinese law, citizens must apply to the local public security bureau five days in advance of a scheduled protest. Applicants must appear in person and offer detailed information about their topic, any possible slogans and the expected number of demonstrators. The law prohibits protests that are deemed harmful to national unity and social stability or that agitate for ethnic separatism. These prohibitions can be interpreted so broadly that most legal protests are not approved.

"We never get it no matter how many times we try," said Jiang Tianyong, a lawyer and legal rights advocate who has been rejected numerous times. "This is only a show for foreigners. Otherwise, I'd love to see these three places be kept after the Olympics, so we can let our voices be heard, too."

Xu Zhiyong, another legal rights advocate, agreed that obtaining approval for legal protests is usually very difficult, but he also applauded the Olympic protest zones as an improvement that should be acknowledged.