Chinese authorities have detained two men for "spreading a rumour" on the Internet that thousands of police officers were deployed to guard a wedding convoy, state media said Monday.

According to the official Xinhua news agency, the two men were detained in the central province of Hunan on Sunday for posting a video clip online showing scores of police officers and a wedding convoy on a street.

But a statement from the Hunan People's Court, posted on the court website Friday, explained that judicial police officers were actually training at a base in Hunan, and happened to pass a wedding convoy on their way out.

Xinhua said the video went viral and received a large number of hits, adding that the two men had been given a five-day administrative detention.

It is the latest in a string of government clampdowns on online "rumours", as it seeks to tighten controls over the Internet -- which now has more than half a billion users in China -- amid fears of social unrest.

The title of the video, posted on popular YouTube-like sites, said "5,000 police officers create the best wedding in Changsha (Hunan's capital)".

Authorities in China are concerned about the power of the Internet to influence public opinion and trigger unrest in a country that maintains tight controls on its traditional media outlets.

Leading Internet firms have already been asked to tighten their grip on the web.

In September, the head of Sina said the web giant -- owner of China's most popular Twitter-like microblogging service, or weibo -- had set up "rumour-curbing teams", apparently in response to government pressure.

Chinese police have already detained several people for spreading a rumour that AIDS patients were trying to transmit the HIV virus by contaminating food in restaurants, state media has reported.

The story triggered huge concern among the public, forcing the health ministry to issue a statement explaining there had never been a case anywhere in the world of HIV being transmitted through food.