Clampdown on Anti-Japan Protests

But China's leader-in-waiting denounces Japan's decision to buy disputed islands.

China's vice-president Xi Jinping, widely regarded as the leader-in-waiting, said on Wednesday that Japan should "rein in its behavior" and stop undermining Beijing's sovereignty, as Chinese authorities clamped down on violent anti-Japanese protests which flared for several days over a territorial dispute.

Tensions between China and Japan, Asia's two biggest economies, have been running high amid four days of major protests in cities across China and with Japanese and Chinese boats gathering in the waters around a disputed island chain in the East China Sea.

Xi said Japan's "purchase" last week of the disputed islands, known as Diaoyu in China and Senkaku in Japan, was a farce, according to the official news agency Xinhua.

"Japan should rein in its behavior and stop any words and acts that undermine China's sovereignty and territorial integrity," Xi said in a meeting with visiting U.S. Defense Secretary Leon Panetta, the agency said.

Meanwhile, Beijing began a nationwide clampdown on anti-Japan protests, prompting hundreds of Japanese businesses and premises to reopen their doors on Wednesday.

"It seems the protests in front of our embassy have subsided," the Japanese embassy in Beijing, the focal point of protests, said in an email to Japanese citizens reported by Reuters.

Anger remains

While many Japanese businesses opened as normal on Wednesday, popular anger over the dispute appears to continue unabated.

An employee surnamed Wei who answered the phone at the National Kaifang University in Beijing said the university had canceled all scholarly exchanges with Japanese universities in the wake of the dispute.

"We were supposed to have an academic exchange with them this month, but now we're not going," Wei said. "A lot of people are concerned about revenge attacks, and for their personal safety."

"We thought we'd wait until things had improved," she said.

A Beijing-based tour operator specializing in tours to Japan surnamed Peng said its business had been hard-hit by recent events.

"We have canceled the tours to Japan," she said. "Even the Sino-Japanese joint venture car factory halted production for two days."

But she said she supported the protesters' viewpoint.

"I think they're right to boycott Japanese goods," Peng added. "But as for rest of it, beating people up and stuff, I think that's going too far."

Anti-Japan protests had intensified across China on Tuesday as the country marked a sensitive military anniversary.

Anti-U.S. slogans

Protesters surrounded a vehicle carrying US Ambassador Gary Locke as his car approached the entrance to the U.S. Embassy in Beijing. Chanting anti-American slogans and hurling plastic water bottles, the crowd caused minor damage to the vehicle before being pushed away by security personnel.

The State Department said embassy officials were "concerned" over the incident. "[They] urged the Chinese Government to do everything possible to protect American facilities and personnel," it said in a statement.

An estimated 2,000 people took to the streets in Beijing, with thousands more demonstrating in several major cities across China.

In the northeastern Chinese province of Liaoning, where the 1931 "Mukden Incident" heralded the Japanese invasion of China, thousands marched to the Japanese consulate in Shenyang, waving banners recalling Chinese shame and anger at Japan's colonial past.

The crowd threw bricks, smashing windows in the building, and holding up placards, but were kept away from the consulate building by riot police.

Macau-based military affairs analyst Huang Dong said China and Japan were still a long way from any sort of military confrontation, in spite of popular anger and the visits made by activists to the area in recent days.

"Relations are gradually improving now, and both parties are looking for a way to back down," Huang said. "Everyone is clear now where the boundaries have been drawn, so I don't think we'll see a military confrontation."

He said the patrol boats that China had sent to the area were on a par in terms of aggressive capability to the Japanese coastguard, which also has a presence in those waters.

"The Japanese can say that they won't be terrorized, while China...wants to ensure a smooth leadership transition, and has taken the opportunity to back off," Huang said.

Meanwhile, Hong Kong-based Diaoyu activist Lo Hom-chau, who traveled to Beijing to sue the Japanese government for "illegally detaining" Diaoyu activists who landed on the island, said security was now quite tight in the Chinese capital.

"When I left the area around the Supreme People's Court, the police escorted me all the way so it was hard for me to meet with the media," said Lo, who returned to Hong Kong after leaving Beijing on Wednesday. "I could only speak on the phone."

"They didn't leave me until I had passed through immigration at the airport," Lo said. "They just followed me, and they behaved pretty well, but it made me feel uncomfortable."

Reported by Qiao Long for RFA's Mandarin service, and by Wen Yuqing for the Cantonese service. Translated and written in English by Luisetta Mudie.