Updated 12:45 p.m. ET Saturday: BEIJING - China's leader-in-waiting Xi Jinping appeared in public on Saturday for the first time in about two weeks, state news agency Xinhua reported, following rumors about his health or the state of the country's leadership succession.

Xinhua said Vice President Xi "arrived at China Agricultural University Saturday morning for activities marking this year's National Science Popularization Day."

Pictures on state television's main evening news showed a healthy-looking, relaxed Xi inspecting ears of corn, chatting with students and laughing with children. Reuters had reported that Xi was likely to make an appearance on Saturday.

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A later, full description of Xi's visit by Xinhua said he inspected exhibitions on growing drought-resistant corn and a talk on how to fight food adulteration, a perennial problem in the world's second-largest economy.

"Food is the people's first necessity, and food safety is an important issue for people's livelihood," the report quoted him as saying.

None of the reports made mention of Xi's recent absence.

Sources have told Reuters Xi hurt his back while swimming earlier this month and that he had been obeying doctors' orders to get more bed rest and undergo physiotherapy.

Xi had been out of the public eye for almost two weeks and had skipped meetings with foreign leaders and dignitaries, including U.S. Secretary of State Hillary Clinton.

Chinese government officials repeatedly refused to say what happened to him, fuelling speculation that has included Xi supposedly suffering a heart attack, a stroke, emergency cancer surgery and even an attempted assassination.

The health of the country's leaders has long been considered a state secret in China.

The ruling Communist Party's refusal to comment on his disappearance from public view and absence from scheduled events was in keeping with its traditional silence on the question of the health of top leaders, but it had worried or mystified most China watchers.

Xi had last appeared in public on September 1. He pulled a back muscle while swimming shortly before Clinton arrived on an official visit on September 4, the sources said, forcing him to scrap a meeting with her the next day and also with Singapore Prime Minister Lee Hsien Loong.

On Wednesday, state media carried comments attributed to Xi for the first time since he dropped out of sight, but there was no public sighting of him or any new photographs.

Beijing has yet to announce formally a date for the party's five-yearly congress, at which Xi is tipped to replace Hu Jintao as party chief, although it is still expected to be held in mid or late October at the earliest.

In March next year, he is formally to take up the reins of the world's second-largest economy.

The uncertainty surrounding Xi's absence has had no impact so far on Chinese or foreign markets, which have been absorbed by Europe's debt crisis and China's own economic slowdown. But investors have been keeping a close eye on the mystery surrounding Xi, after months of high political drama in China.

Senior leader Bo Xilai was suspended from the party's 25-member Politburo in April and his wife convicted of the murder of a British businessman. Blind human rights activist Chen Guangcheng escaped from house arrest in April and took refuge in the U.S. embassy before leaving for New York.

In another scandal this month, a senior ally of President Hu was demoted after sources said the ally's son was killed in a crash involving a luxury sports car.

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