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. That's according to the Washington Post.

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 Cooperation Meeting, where the US president interviewed Ma, then China's second-richest man, in front of a crowd of business executives.