By Sharon LaFreniere, New York Times, March 3, 2011

BEIJING — Apparently unnerved by an anonymous Internet campaign urging Chinese citizens to emulate the protests that have rocked the Middle East, Chinese authorities this week have begun a forceful and carefully focused clampdown on activities by foreigners that the government deems threatening to political stability.

Public security officials have summoned dozens of foreign journalists in Beijing and Shanghai to be dressed down on videotape, warning them that they had broken reporting regulations by visiting locations that had been selected as protest sites in Internet postings. Journalists were bluntly warned that they faced the loss of their visas, revocation of their credentials and expulsion if they did not abide by new limits on their ability to interview and photograph Chinese citizens.....

Separately, Beijing officials announced Wednesday that they intended to monitor the movements of millions of residents by means of information transmitted by their cellphones. One official was quoted on a government Web site as saying that the new program would provide “real-time information about a user’s activity.”

The project aims to monitor all Beijing residents who use cellphones — about 20 million people — to detect unusually large gatherings. One official said the primary use would be to detect and ease traffic and subway congestion. But Chinese media reports said government officials could use the data to detect and prevent protests. ....

Some who tried Sunday to look into vague, Internet-based calls for protests paid a price. In Beijing, plainclothes officers dragged reporters and photographers into alleys or shops and erased images from their cameras. Three journalists were injured, including a Bloomberg News videographer who was kicked and beaten, according to the correspondents’ association.

This week, public security officials warned reporters from The New York Times, The Associated Press, Agence France-Presse and numerous other foreign news organizations that they had violated regulations by appearing at possible protest sites and that further infractions would not be tolerated....