Working 9-5? Not if you're employed by Alibaba founder Jack Ma.

Key points: Alibaba founder Jack Ma told his staff that working 12 hours a day was a "blessing"

Alibaba founder Jack Ma told his staff that working 12 hours a day was a "blessing" It came after fellow e-commerce titan Richard Liu called workers "slackers"

It came after fellow e-commerce titan Richard Liu called workers "slackers" Mr Ma later walked back his comments after criticism from Chinese state media

China's wealthiest man, with an estimated net worth of more than $50 billion, has created a stir on social media after declaring that staff should adhere to a "996" work schedule: from 9:00am to 9:00pm, six days a week.

The 72-hour work week — nearly double the Australian standard of 38 hours a week — has become a subject of controversy in China as tech firms place increasingly high expectations on workers.

In a speech to Alibaba staff that was posted to Weibo, Mr Ma said working 12 hours a day for the company was a "blessing".

"If you don't work 996 at a young age, when will you be able to [do it]? Do you think never having to work 996 in your life is an honour to boast about?" he said.

"How can you achieve the success that you want without exceeding other people's effort and time?"

However, the tech billionaire later appeared to walk back his comments after facing criticism from netizens — as well as Chinese state media.

"If you find a job you like, the 996 problem does not exist — if you're not passionate about it, every minute at work is torture," he said in the lengthy post to Weibo.

Mr Ma poses with employees ahead of the company's initial public offering at the New York Stock Exchange. ( Reuters: Brendan McDermid )

"No one likes working at a company that forces you to do 996. Not only is it inhumane, it's unhealthy and even more unsustainable for long periods — plus workers, relatives and the law do not approve of it.

"In the long term, no matter how high the salary you pay your employees, they will all leave."

China's gruelling overtime work culture

His comments came as Richard Liu, the founder of Chinese e-commerce giant JD.com, also weighed in on the ongoing debate about the Chinese tech industry's gruelling overtime work culture, lamenting that years of growth had increased the number of "slackers" in his firm.

Mr Liu posted on WeChat that in the firm's early days he would set his alarm clock to wake up every two hours so he could offer his customers 24-hour service — a measure he called crucial to JD's success.

JD.com founder Richard Liu founded his e-commerce site back in 1998. ( Reuters: Bobby Yip )

"JD in the last four, five years has not made any eliminations, so the number of staff has expanded rapidly, the number of people giving orders has grown and grown, while those who are working have fallen," he wrote. "Instead, the number of slackers has rapidly grown!"

"If this carries on, JD will have no hope! And the company will only be heartlessly kicked out of the market! Slackers are not my brothers!" he added.

The comments are the latest contribution to a growing discussion about work-life balance in the tech industry as the sector slows after years of breakneck growth.

In an editorial published on Sunday, Chinese communist party mouthpiece the People's Daily newspaper censured the Alibaba and JD.com leaders for their statements, saying that doing "forced overtime" is not equivalent to "working hard".

"With the pressure of economic downturn, many enterprises are facing challenges to survive … but the way to relieve anxiety is not to let employees work overtime as much as possible," the editorial said.