BEIJING - Angry demonstrators attempted to storm the Japanese embassy in Beijing Saturday, state media said, as tens of thousands of people across China protested against Japan over a growing territorial dispute. Riot police armed with batons and shields struggled to contain the swelling crowd outside the embassy, where witnesses said at least 2,000 people had gathered, some of them throwing stones and plastic bottles at the building. A mob attempted to break into the embassy compound but were stopped by armed police, the state news agency Xinhua said. It estimated the crowd at several thousand at its peak. Meanwhile, there were online reports that protests were staged in at least a dozen cities across China, with Japanese-built cars and Japanese restaurants being attacked by angry crowds. Japanese media estimated 40,000 people took part in the protests nationwide. On China’s Sina Weibo, a microblog similar to Twitter, images were posted of protests in the southwestern cities of Chongqing and Kunming. Rallies were reported in several other places including the eastern city of Nanjing and Xian and Taiyuan in the north. Much of the information about the protests posted online appeared to have been removed by the afternoon by China’s army of Internet censors — suggesting that Beijing is aiming to stop the row from spiralling further out of control.