Chinese Vice President Xi Jinping has made his first public communication in nearly two weeks, state media said Thursday, amid swirling speculation about the whereabouts of Beijing's leader-in-waiting.

Xi has not been seen in public for 13 days and has cancelled meetings with four foreign dignitaries including US Secretary of State Hillary Clinton, giving rise to intense speculation about his health.

His unexplained disappearance has come at a highly sensitive time for China, which is gearing up for a generational handover of power that has already been marred by two major political scandals involving senior communist officials.

On Thursday, 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. His reported ailments have ranged from a heart attack to a back ache.

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, but noted that the heir apparent called off meetings not only with Clinton but with other foreign dignitaries.

"Of course you are all speculating as to what's happening with Vice President Xi, but it appears it had nothing to do with Secretary Clinton or the US government," Locke said at the Carnegie Endowment for International Peace.

The country's tightly controlled state-run media has ignored the issue, focusing instead on a row over Japan's purchase of the disputed Diaoyu islands, known in Japan as the Senkaku islands.

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".

The dates of previous party congresses have been announced months in advance, and some experts have suggested the delay in announcing the schedule for this year could be linked to Xi's absence from public view.

However, analysts of Chinese politics 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.