Thousands of college students in southwest China's Chongqing Municipality took to the streets in heavy rain Tuesday to assert China's claim to sovereignty over the Diaoyu Islands.

The protest began at around 2 pm when 500 college students marched through downtown Chongqing, holding banners saying "Object to Japan's invasion of the Diaoyu Islands."

The protestors passed the Japanese consulate in Chongqing, but were kept away from the building by police.

Then they marched to a square with a monument that commemorates people killed by Japanese invaders during World War II.

The crowd increased to several thousand people at around 3:30 pm, the Xinhua News Agency reported.

AFP reported, quoting an official at the Japanese consulate in Chongqing, that 2,000 people joined the demonstration.

Groups of police came to the square at around 3:40 pm and started to persuade the students to leave. No violence was reported in the protest, which ended at around 4:30 pm, but it caused a serious traffic jam.

Students in Chengdu, Xi'an, Zhengzhou took to the streets in similar protests earlier.

China-Japan relations have been strained since a collision between two Japanese Coast Guard patrol ships and a Chinese trawler on September 7 in the East China Sea off the Diaoyu Islands.

Officials have earlier reminded protestors to express patriotism in a rational way. An opinion article posted by people.com.cn said expressing patriotism irrationally may affect the country's social order, economic growth and peaceful life of its people.