(Reuters) - Chinese defense minister Li Shangfu abruptly pulled out of a meeting with Vietnamese defence leaders last week, three officials with direct knowledge of the matter said, amid questions about his more than two-weeks-long absence from public view.

Li, 65, was due to attend an annual gathering on defense cooperation hosted by Vietnam on its border with China on Sept. 7-8 but the meeting was postponed after Beijing told Hanoi days before the event that the minister had a "health condition," two Vietnamese officials said.

The sudden postponement of the meeting and the reasons cited by China are being reported by Reuters for the first time.

China's State Council Information Office, as well as its defense and foreign ministries did not immediately respond to a request for comment about the Vietnam event. The Vietnamese embassy in Beijing couldn't immediately be reached for comment Thursday evening.

The abrupt cancellation of Li's trip follows China's unexplained replacement of Foreign Minister Qin Gang in July after a prolonged absence from public view and a shake-up of the leadership of the People's Liberation Army's elite Rocket Force in recent months, moves that have raised questions about the Chinese leadership's decision-making.

Qin's meteoric ascent through the ranks of the Communist Party was partly attributed to his closeness to President Xi Jinping, making his removal after just seven months on the job even more unexpected. Chinese officials initially said Qin's absence from public view was due to health reasons.

Li was appointed to his post in March. He is watched closely by diplomats and other observers because, like Qin, he is also one of China's five State Councillors, a cabinet position that ranks higher than a regular minister.

A U.S. official, on condition of anonymity, said Washington was aware of Li's cancelled meetings with the Vietnamese. U.S. President Joe Biden visited Hanoi last week, where the two sides inked a historic upgrade of their partnership.

Li's prolonged absence from public view has drawn some comment. U.S. Ambassador to Japan Rahm Emanuel posted on X, formerly Twitter, on Sept. 8: "First, Foreign Minister Qin Gang goes missing, then the Rocket Force commanders go missing, and now Defense Minister Li Shangfu hasn't been seen in public for two weeks. Who's going to win this unemployment race? China's youth or Xi's cabinet?"