More than 30 political advisers from the worlds of art, culture and entertainment have backed a proposal calling for a law to safeguard China's "national dignity".

The move comes after a series of incidents in which young Chinese people have been accused of disrespecting victims of the Nanjing Massacre by visiting memorials and other historic locations dressed as imperial Japanese soldiers.

"Making fun of a national disaster or people's pain challenges the bottom line of justice and human nature," He Yun'ao, a member of the National Committee of the 13th Chinese People's Political Consultative Conference, said during a group discussion on Thursday.

He, who is a history professor at Nanjing University in Jiangsu province, proposed drafting a law to deter such behavior. His motion was supported by other members, including Hong Kong movie star Jackie Chan.

According to official statistics, more than 300,000 people were killed in just six weeks after Japanese troops captured Nanjing on Dec 13, 1937.

This week, a man from Shanghai was detained for the second time in two months for offensive remarks online about those who lost their lives.

The 35-year-old, identified only as Meng, was held for 15 days in February for saying in a WeChat group that the massacre victims had deserved their fates. This month, he was detained for another eight days for recording a video outside the Memorial Hall for the Victims of the Nanjing Massacre to insult the netizens who reported him.

Also in February, two men wearing costumes designed to look like imperial Japanese military uniforms took selfies in front of a historic battlefield site in Nanjing.

Four men in similar outfits also posed for pictures in August outside Sihang Warehouse, a Shanghai landmark where Chinese soldiers held off invaders for days during the War of Resistance Against Japanese Aggression (1931-45).

Each incident resulted in a public outcry, yet current law defines such actions as disturbing public order, which carries a maximum punishment of 15 days in detention.

Foreign Minister Wang Yi denounced those who carry out such stunts as "scum" at a news conference on Thursday.

He Yun'ao, the history professor, said: "We must bring people's voices to the two sessions. Desecrating war heroes and excusing the Japanese forces' atrocities is a mockery to Chinese people's lasting resistance against the invaders. It insults our national dignity. I'm not targeting the individuals but looking for reasonable solutions."

Insulting the national flag, anthem or emblem are now crimes in China, and He said his proposed law would give "national dignity" equal status.

"We still need more solid legal references when talking about how to punish those who publicly promote fascism or Japanese militarism, or who insult revolutionary martyrs and national heroes," he added.

Actor and director Zhang Guangbei was among the political advisers who backed the proposal. To show his support, he quoted a line from his best-known role, as general Chu Yunfei in Drawing Sword: "National interests should come above all else."

TV director Zheng Xiaolong added that the unrealistic portrayals of combat in some recent Chinese productions made the war eight decades ago look like a game and had negatively influenced viewers' perceptions.

Feng Yuanzheng, an actor from Beijing People's Art Theatre, also endorsed the proposal and said the issue reflected problems in education.

"Offenders cannot be explained away as naive," he said. "It will harm our country if the young generation blindly admires foreign cultures. There should be rules to let people know where the red line is."