Chinese Foreign Ministry spokesman Ma Zhaoxu on Saturday night commented on demonstrations in some Chinese cities against Japan over the Diaoyu Islands, saying such protests are "understandable" but patriotism should be expressed rationally and in line with law.

Ma made the remarks when asked to comment on the demonstrations by thousands of Chinese, who took to streets Saturday in cities including Chengdu, Xi'an and Zhengzhou to assert China's claim to sovereignty over the Diaoyu Islands.

"It is understandable that some people expressed their outrage against the recent erroneous words and deeds on the Japanese side," Ma said.

"We maintain that patriotism should be expressed rationally and in line with law. We don't agree with irrational actions that violate laws and regulations," he noted.

China and Japan are important neighbors to each other, and there exist between them some sensitive and complicated issues, Ma said.

"We advocate properly resolving those issues through dialogues and making joint efforts to safeguard the strategic bilateral relationship of mutual benefit," Ma said.

China-Japan relations have been strained since a collision occurred between two Japanese Coast Guard patrol ships and a Chinese trawler on Sept. 7 in the East China Sea off the Diaoyu Islands, over which China claims sovereignty.

Also on Saturday, hundreds of Japanese right-wing organization members demonstrated in front of the Chinese Embassy in Tokyo to "clarify Japanese's attitude on the issue."