BEIJING — China's capital is tightening security around the highly symbolic Tiananmen Square ahead of this summer's Olympic Games.

New rules issued by the city government ban dangerous articles, including guns, explosives, knives and "other items that affect social order and public safety."

The rules, enacted last month but announced only Monday, also allow random searches of people and vehicles in the area around the vast plaza in the heart of Beijing. They also permit authorities to take unspecified emergency measures to disperse crowds.

The rules don't specifically mention the Olympics, but come amid an overall tightening of security in and around Beijing ahead of the games. While security in the square is routinely stepped up on sensitive dates, the rules give authorities a legal basis for more clearly defined measures and a mandate to carry them out for an indefinite period.

Tiananmen Square is China's most politically charged public space and authorities are desperate to avoid embarrassing incidents that could tarnish the Olympics, which the Communist leadership sees as a crowning achievement and source of massive national prestige.

The square sits in front of the ceremonial legislature and has been the site of anti-government protests, including the 1989 student-led pro-democracy movement that was crushed by the People's Liberation Army.

Underscoring sensitivity about the square, China has told broadcasters it will bar live television shots from Tiananmen during the games — disrupting the plans of NBC and other international networks that have paid hundreds of millions of dollars to broadcast the Aug. 8-24 games and were counting on eye-pleasing live shots.

The move was apparently linked to recent unrest among Tibetans and a wave of passionate protests by critics of the Communist government that followed the Olympic torch on its journey around the world last month.

Other aspects of Beijing's Olympic security regime have not been announced, although there is a marked increase in the number of police and paramilitary troops in the center of the city.

China also has tightened visa restrictions and monitoring of residency permits for foreigners.