An envelope containing a harmless white powder was sent to the Chinese Embassy in Tokyo on Friday, police said Saturday.
The police are investigating the case as harassment following a spate of anti-Japan rallies in China, police officials said. The incident is a throwback to the anthrax scare after the Sept. 11, 2001, attacks in the United States.
The envelope was delivered to the embassy Friday morning. An employee opened it in the afternoon and found about 0.2 gram of powder, they said.
There was nothing else in the envelope, which had a postmark indicating it was mailed Wednesday in Yamagata Prefecture, they said.
On Friday night, a mailbox doorplate and intercom at the Minato Ward residence of Chinese Ambassador Wang Yi were found sprayed with red paint. The police believe the vandalism was also in response to growing tensions between the two countries.
According to the Chinese Embassy, a razor was sent to the Chinese Consulate in Nagasaki on Tuesday.
China tours canceled
Anti-Japan protests in China have resulted in some cancellations of group and independent tours, Japanese airlines and travel agencies said Saturday.
Some tourists changed their destinations to Taipei or to domestic trips in the past week over fears that anti-Japan demonstrations will continue, according to some airlines.
"Companies are calling on their employees to avoid unnecessary business trips, and such moves are having an impact (on our business)," a Japan Airlines Corp. spokesperson said.
Meanwhile, at least three high schools in Shimane, Hiroshima and Aomori prefectures have canceled excursions to China due to security concerns.