Thousands of protesters gathered in front of the embassy in Beijing. Hundreds tried to storm a metal barricade backed by riot police armed with shields, helmets and batons. Many threw rocks, bottles, eggs and traffic cones at the embassy.
The embassy said protesters around the country set fire to Japanese factories, sabotaged assembly lines, looted department stores and illegally entered Japanese businesses.
"We express regret over what has happened today and ask the Chinese government to ensure the safety of Japanese citizens and businesses in China," it said in a statement.
Anti-Japanese sentiment, never far from the surface in China, has been building for weeks, touched off by moves by Tokyo and fanned by a feverish campaign in Chinese state media. Passions grew more heated this past week after the Japanese government purchased the contested East China Sea islands from their private Japanese owners.
Japan's Kyodo News agency said more than 60,000 people protested in at least 28 Chinese cities, making the anti-Japanese demonstrations the largest since the two countries normalized diplomatic relations in 1972. The protests were expected to continue Sunday.
