Four men were criticized online after posing for pictures dressed in Imperial Japanese Army uniforms in front of a stronghold used by Chinese soldiers to repel Japanese invaders during the Battle of Shanghai in 1937.

The photos, which show the men standing in front of the historic Sihang Warehouse, began circulating late on Monday. Many people commented online that it was disrespectful.

"My grandfather was one of the soldiers in that battle and he died," one internet user wrote on Sina Weibo. "Those who sacrificed their lives for the country and the people should never be forgotten or insulted, especially at the same place where they died."

A military enthusiast in Beijing, who said he knew the four men from an online chat group for fans of military products, told China Daily that all of them are university students pursuing undergraduate or graduate studies, and they collect Japanese military memorabilia.

"Each collector of military artifacts gives different reasons, such as the weapons, the uniform, the war history or the culture. But collectors of Japanese items are usually very cautious," said the man, who gave only his surname, Song.

"For most such collectors, the intention is to remember history and make the public aware of it to alert future generations," he said, adding that the four men came from Beijing and Sichuan province.

Song said people in the chat group are criticizing the four for their unreasonable and immoral activities and encouraged them to make a public apology.

The four declined to comment.

On Saturday, two Chinese tourists, aged 36 and 49, were arrested in Berlin and charged with making Nazi salutes while posing for pictures in front of German parliament.

Police officers patrolling nearby arrested the two, who were charged under the country's post-1945 laws that prohibit hate speech and symbols associated with Hitler and his Nazi followers.

The Chinese embassy in Berlin said on Monday that each of the two was fined 500 euros ($586) and left Germany without further criminal punishment, Xinhua News Agency reported.

He Jianmin, a professor at Shanghai University of Finance and Economics, who specializes in tourism management, said China should make laws to forbid behavior betraying national dignity and patriotism at special sites.

The State Administration of Cultural Heritage on July 31 began soliciting public opinion on a document regarding the preservation and use of cultural relics relevant to the War of Resistance Against Japanese Aggression (1931-45).

The document makes it clear that all visitors to such sites should dress properly and remain silent.

zhouwenting@chinadaily.com.cn