Activists have called on the founder of Chinese e-commerce giant Alibaba Group to apologise over remarks in which he appeared to condone the bloody Tiananmen Square crackdown in 1989.

Jack Ma suggested in an interview with Hong Kong's South China Morning Post that the order by former Chinese leader Deng Xiaoping to break up the student protest was necessary for China's stability.

The Internet mogul said that as chief executive of Alibaba there were times when he had to make "cruel" decisions "like Deng Xiaoping, the then-top leader, had to make cruel decisions during the June 4 crackdown for the country's stability".

Hundreds, perhaps thousands of pro-democracy protesters were killed in the military crackdown on June 3-4 in Beijing.

China has never provided an official final toll for the incident, which was condemned worldwide.

The Chinese Communist Party branded the protests a "counter-revolutionary rebellion". Mention of the incident has long been strictly censored on the Internet in China, where schools are banned from discussing the events.

Ding Zilin, spokeswoman of the Tiananmen Mothers, a group representing families of the victims, accused Ma of "lacking conscience" over the remarks.

"This was not out of ignorance. This was lack of conscience. He is a businessman. He should not compare himself with youngsters who have been deceived," Ding told AFP.

Alibaba could not immediately be reached for comment.

Founded by Ma, the Alibaba Group also runs Taobao, the most popular online shopping platform in China.

The company is mulling an initial public offering abroad, which analysts say could value it at between $60 billion and $100 billion.

Ma stepped down as the company's chief executive officer in May, handing over the job to Lu Zhaoxi, previously executive vice president, but remains chairman.