Jack Ma reacts during a session at the Boao Forum for Asia Annual Conference 2018 on April 9, 2018 in Boao, China.

Alibaba co-founder Jack Ma has been a member of China's Communist Party since the 1980s, a person familiar with the matter told CNBC on Tuesday.

The person asked to remain anonymous because they were not authorized to speak publicly on the subject.

A report by state-backed People's Daily released a list of people on Monday that the Communist Party wishes to honor for "their contributions to the reform and opening up." Ma was among the names mentioned, which drew questions about when he had joined the country's ruling party.

Ma's Communist Party membership status had long been a question. Although Chinese-language websites as early as 2015 said he was a party member, those had not been widely noticed by the international community. This week's news, however, revealed that the man reported to be China's richest is also a long-time member of a group that can trace its roots to Karl Marx.

State-run Chinese media on Tuesday reported on a social media post from someone claiming to be a former classmate of Ma's, who said that they joined the Communist Party while in university.

"We all joined the party around the second or third year of university. Back then, joining the party meant not just that you were a good student, but also that you had integrity, organizational ability, enthusiasm and idealism," the post said, according to a translation that matched a screenshot of the post seen by CNBC.

The news comes after Ma announced plans to step down as chairman of Alibaba in September.

There had been speculation for some time that Ma was a member of the party but nothing had been confirmed until the recent report. But the person familiar told CNBC that Ma has indeed been a Communist Party member since his university days in the 1980s.

Alibaba, through a spokeswoman, declined to comment on Ma's party membership history.

Two other top leaders of China's non-governmental technology sector were also mentioned on the People's Daily's list of people who have helped open up China, although both are "non-partisan" and not party members: Tencent CEO Pony Ma and Baidu CEO Robin Li.

Correction: Pony Ma and Robin Li were not listed as Communist Party members on the People's Daily list.