Jack Ma, chairman of the China Entrepreneur Club and chairman of the Alibaba Group. [Photo provided to chinadaily.com.cn]

Jack Ma, the billionaire chairman and founder of China's e-commerce conglomerate Alibaba Group, paid a secret visit?to the White House on Tuesday, The Washington Post reported.

The newspaper said reporters had spotted Ma leaving the White House grounds with several aides and at least two security guards.

Ma declined to comment other than to simply say his meeting with US President Barack Obama was "very good".

A White House spokesperson confirmed that Obama had lunch with Ma but offered no other details of their meeting. The lunch meeting was not listed on the US president's public schedule.

The newspaper cited White House Press Secretary Josh Earnest as saying Obama and Ma have shared a stage in Malaysia last November during the Asia-Pacific Economic Summit, where the US president interviewed Ma, then China's second-richest man, in front of a crowd of business executives.

Ma overtook China's property giant Dalian Wanda's Wang Jianlin to become Asia's richest man in April after his company's affiliate Ant Financial raised a new financing round of $4.5 billion.

That added $4.3 billion to Ma's fortune, bumping his wealth to $33.3 billion, according to the Bloomberg Billionares Index.