China's Vice-President Xi Jinping has made his first public appearance in two weeks, state media said on Saturday, following swirling speculation about the whereabouts of Beijing's leader-in-waiting.

Xi had not been seen in public since September 1 and cancelled meetings with four foreign dignitaries including visiting US Secretary of State Hillary Clinton, giving rise to intense speculation about his health.

The vice-president arrived at China Agricultural University in Beijing on Saturday morning for 'activities marking this year's National Science Popularisation Day', Xinhua said.

Two pictures released by the state-run news agency showed a relaxed Xi speaking to a group of men at the university.

They were also posted on the government website, and were carried by several domestic online news portals.

China's tightly controlled state-run media has ignored Xi's disappearance from public view, focusing instead on a row over Japan's purchase of the disputed Diaoyu islands, known in Japan as the Senkaku islands.

News broadcasts up to the 11am (0300 GMT) bulletin on the state-run China Central Television on Saturday made no mention of Xi's public appearance.

His unexplained disappearance came at a highly sensitive time for China, which is gearing up for a generational handover of power.

On Thursday, he made his first public communication in nearly two weeks when state media said he had 'expressed condolences on the death of old party comrade Huang Rong', who died on September 6 -- a day after Xi missed a planned meeting with Clinton.

The report in the Guangxi Daily newspaper -- mouthpiece of the Communist Party committee in China's southern Guangxi region -- marked the first public communication by Xi since he delivered a speech on September 1.

The news was published widely in China, but made no mention of Xi's health, which has been the subject of widespread speculation in recent days. Theories about his health have mentioned anything from backache to a heart attack.

Xi has been widely tipped to succeed President Hu Jintao as leader of the ruling Communist Party at a crucial meeting that is expected to be held sometime next month, before taking over as head of state in March.

His disappearance from public view has attracted global attention, as well as some speculation on China's popular but heavily censored microblogs.

US Ambassador to China Gary Locke declined to weigh in on Xi during an appearance in Washington earlier this week, but noted that the heir apparent called off meetings not only with Clinton but with other foreign dignitaries.

China's government has so far given no explanation for his absence. At a daily media briefing on Thursday, foreign ministry spokesman Hong Lei refused for the fourth day running to answer repeated questions about Xi's whereabouts.

Hong did, however, say that preparations for the 18th Communist Party Congress -- where Xi is expected to be named party leader -- were 'well under way', adding that 'Chinese authorities will release relevant information in due course'.

Analysts say Xi is likely suffering from a relatively minor health complaint, as anything more serious would have prevented Hu from leaving the country to take part in last week's APEC summit.