Beijing — China is clamping down on fun for the Olympics, closing bars and clubs and making it more difficult for companies to provide their usual lavish hospitality parties for clients.

In the lead-up to the Games, the authorities have launched a sweep of Beijing, expelling thousands of foreign prostitutes and outsiders without the proper residence papers.

But they are also restricting visas, threatening to implement entertainment regulations that were previously laxly enforced, and slowing delivery of permits and paperwork.

Owners of bars and other businesses say an obsession with rules and security risks squeezing the enjoyment out of the Games.

“It’s all proving extremely difficult and getting more difficult the closer we get,” Tom Seymour, the Chinese representative of Elite Sports, which runs corporate hospitality events, said.

He said his company’s program of parties where clients met athletes represented by his firm had been cut to just one, from 17 at the Sydney Olympics. Some major brand names had also dropped party schedules, he said.

Beijing has recently developed a reputation, surprising considering its recent history, as one of Asia’s most “happening” cities. It is the center of the Chinese rock and modern art scenes, while new restaurants, bars, and nightclubs open every week. But earlier this month, in a sign of the Communist Party’s residual distrust of influences from outside, the authorities issued a list of 57 rules for foreigners coming to the Olympics.

Many were restatements of existing laws, but some caught even Beijing residents by surprise. One rule “reminded” visitors that bars and clubs shut at 2 a.m. — a rule of which many were unaware since there is no sign it has been implemented in recent years.