Giggling together, arm-in-arm as they clutched designer handbags and iPhones, the teenage girls' faces contorted with anger as they screamed in unison "Japan leave Diaoyu, China fight, fight, fight!"

The transformation of the foursome as they joined an anti-Japanese protest outside Tokyo's embassy in Beijing on Tuesday was a stark illustration of the animosity some Chinese harbour towards their neighbours.

The sentiment has been heightened by fury over uninhabited but disputed islands in the East China Sea, known as Diaoyu in China and Senkaku in Japan, which Tokyo controls but Beijing proclaims as its "inalienable territory".

Protesters carried signs reading "Kill Japanese" and held aloft mocked-up placards showing the Japanese prime minister's face imposed on the body of a dog and a picture of a Chinese soldier stabbing a Japanese enemy.

Dozens of protesters also carried portraits of Mao Zedong.

Mao, the 'Great Helmsman', who critics blame for millions of deaths, remains a divisive figure in Chinese society, but one who is venerated by some for unifying the country and standing up to the invading Japanese army.

"Mao is my spiritual leader, that is why I carry his portrait," said one protester, who reeled off a list of historical crimes he said Japan had failed to apologise for.

Among them was the September 18, 1931, "Mukden Incident" in which Japanese soldiers blew up a railway in Manchuria as a pretext to taking control of the entire northeastern region, which is commemorated every year in China.

Tuesday's anniversary of the historical humiliation added further bitterness to the protest.

Another demonstrator said Mao was the only leader in Chinese history who was not afraid to fight for his country.

"The government will only protest and talk these days, but there has been little action since Mao," he told AFP.

Despite the threatening words and placards, many of the protesters were in a carnival mood, but police were taking no chances.

Six rows of armed officers lined up outside the main gates to the embassy compound ready to protect the buildings in case sentiment boiled over.

"Diaoyu Island is Chinese and we should protect it from Japan. I believe this strongly, and that is why I have come to this demonstration," Jiu Longtou, a 31-year-old factory worker told AFP.

"China is not a weak country any more. We are strong and we should no longer be bullied by Japan."