BEIJING — China acknowledged for the first time today that it is tightening its visa policies ahead of the Olympic Games.

"We have made some arrangements according to usual international practice. That is, in the approval process we are more strict and more serious with the procedure," Foreign Ministry spokesman Qin Gang said.

He did not directly link the changes to the Aug. 8-24 Beijing Olympics, but said the policies would "be maintained for a period of time."

"What is unchanged and will not change is safeguarding our national security and making sure our environment is safe and making sure foreigners in China will be safe," he told a news conference.

Travel agents in Hong Kong, a major gateway to mainland China, reported last month that the government visa office told them multiple-entry business visas would not be available from mid-April until mid-October. In the past, such visas were easily obtainable.

However, Qin said it was not true all multiple-entry visas had been suspended. He did not give further details.

"The Chinese government and people will continue to adhere to the policy of opening and reform, and we will continue to be open to the world. We welcome foreigners to come to China to study, work and travel," he said.

More rules including additional documentation for business visas and hotel bookings and plane tickets for tourist visas have also been reported.

Adding to the confusion was China's continued insistence that no changes had been made to its visa policy.

Both the American and European chambers of commerce in Hong Kong sent letters to the Chinese government last month, citing several cases of visa denials and raising concerns over the impact on businesses.