BEIJING — Airlines are being told to stay away from Beijing's airport during the opening ceremony of the Olympics and further scrutiny is being applied to foreign entertainers in the latest security moves ahead of next month's games.

No official announcement has been made, but local media and airlines said today that the Beijing airport will close for about four hours during the opening ceremony, affecting dozens of flights.

Hong Kong-based Cathay Pacific said it would postpone one flight after receiving word from Chinese authorities recently that the airport would be closed during the opening ceremony, set to begin at the auspicious time of 8 p.m. on Aug. 8.

"We are being informed that the Beijing International Airport will be closed from 7 p.m. to midnight," Cathay Pacific spokeswoman Carolyn Leung said in Hong Kong.

The flight from Hong Kong was scheduled to arrive at 9:45 p.m. but will instead land at 1 a.m. the next day, she said.

A man from customer service line of Olympic sponsor Air China said they received a notice a few days ago saying the airport would be closed during that period.

But a spokesman from the airport denied the reports, saying they welcomed all flights to Beijing. He would not want to give his name, as is common with officials in China.

The warning for the entertainers appears to be part of a wide-ranging set of measures China has put in place ahead of the Olympic games to stop not only political protests but also physical attacks.

Performance rules, which were first introduced in 2005, are being reinforced to guard against entertainment that could tarnish the country's carefully cultivated image of order and control. Authorities were alarmed in March after Icelandic singer Bjork shouted "Tibet! Tibet!" at the end of her concert in Shanghai.

Authorities said her outburst "broke Chinese law and hurt Chinese people's feelings," and vowed to be stricter on foreign performers.

The notice on the Ministry of Culture's Web site on Thursday said China should strengthen rules about foreign performers, including checks on their backgrounds.

"The content of the performance should not violate the country's law, including situations that harm the sovereignty of the country," the notice said, adding that they should also not harm "national security, or incite racial hatred and ruin ethnic unity."

Musicians in Beijing have gone into hibernation this summer as live performances have been stopped in bars, a music festival canceled and clubs suddenly told they need a live performance license.

The South China Morning Post reported today that the crackdown on bars included police forcing bar managers in the popular Sanlitun district to sign agreements pledging not to allow black people into bars during the Olympic Games, as well as other "undesirable" elements.

But local authorities and bar managers denied the report.

"We have just confirmed that no such thing happened. We recommend that you go to the bars there at night and check. You will find that there're still a lot of black people inside," said an official from the propaganda office of the police station that overseas Sanlitun. As is common with many Chinese officials, he would give only his surname, Li.

The manager of the Rickshaw, a popular watering hole open 24 hours, said she had not received such a warning, and expected to welcome visitors of all kinds during the Olympics. She refused to give her name.

Will Bernholz, a manager with Kro's Nest, a chain of popular pizza restaurants, said bars and restaurants have been closed in the lead-up to the Olympics.

"We've all felt the impact of the Olympics really hurting the social scene ... but people are going to make do, people are going to go where they can," he said.

One branch of the Kro's Nest closed down today because it was inside the gates of Worker's Stadium, where several of the Olympic football games will be played.