BEIJING — Chinese police were expected to release two men allegedly involved in stopping Japanese Ambassador Uichiro Niwa's official car in Beijing last week and ripping the Japanese flag from the vehicle, sources said Wednesday.

The Beijing Public Security Bureau earlier told the Japanese Embassy that the suspects — a 23-year-old man from Hebei Province and a 25-year-old man from Heilongjiang Province — were detained Aug. 29 and were being held for five days under a law on public security administration. The administrative penalty was imposed Friday after they owned up to the offense.

The law grants police the authority to hold suspects up to 15 days and to impose fines of up to 1,000 yuan (about ¥12,300) for minor offenses such as damaging property.

The incident, which occurred on a major thoroughfare Aug. 27, took place amid widespread anti-Japan demonstrations in China after Japan arrested a group of Hong Kong-based activists who landed on the Senkaku Islands, which are claimed by China, earlier last month.