Xi Jinping, the Chinese vice-president, has appeared in public for the first time in a fortnight, in an apparent attempt to quash speculation that he is seriously ill or caught up in a power struggle that could threaten a smooth leadership transition in China.

Mr Xi, who is rumoured to have hurt his back while swimming, showed up on Saturday at an event to mark National Science Popularisation Day at China Agricultural University in Beijing.

The official Xinhua news agency published two photographs of the 59-year-old dressed in casual clothes, strolling with other officials. He was reported as saying: “Food safety is a significant livelihood issue,” at an exhibit showcasing instant tests for melamine in milk products. Excess melamine in Chinese infant formula sickened hundreds of thousands of children four years ago, and killed six.

The absence from the public eye of the man expected to take the helm of the world’s most populous nation in less than a month had caused speculation that he might be unable to assume that role, either because of serious illness or because a power struggle might unseat him.

His decision to cancel several appointments in the past fortnight, including a meeting with Hillary Clinton, US secretary of state, led to rumours ranging from an assassination attempt against him, to liver cancer.

The once in a decade leadership transition has already been disrupted this year by the purging of a senior Communist party leader, Bo Xilai. Mr Xi’s absence had heightened speculation of tensions at the top of the country’s elite.

Beijing has still not commented on the reason for his absence, and the media stories on Saturday were very brief. The level of secrecy in China is so great that Chinese citizens may never know the reason for his absence, and many would not have been aware that he was out of sight in the first place.

Internet reaction to Mr Xi’s appearance was muted by the fact that posts including his name were blocked by government censors. However some people questioned whether the pictures published by Xinhua were current.

One post on Tencent Weibo microblog, from Yu Shuo Huan Xiu, said: “You finally appeared in our sights after being called a great many times. From now on, all the rumours are scotched; the heavy seas returned to quiet; sealed walls are replaced by transparent and smooth glass. The rumours and waves could have been avoided.”

China is due to hold its 18th party congress in mid-October at which Mr Xi is expected to take the reins of the Communist party from Hu Jintao, the Chinese president.

Copyright The Financial Times Limited 2018. All rights reserved.