The top university -- from which the likes of politburo member Li Keqiang, widely touted to replace Premier Wen Jiabao in five years, graduated -- will be closed to visitors from July 20 to September 18, Xinhua news agency reported.

The ban will be imposed due to security concerns, Xinhua said, quoting Xing Jinsong, deputy head of the university's campus security department. Teachers, students and staff will have to show identity cards or passes issued by the university to get onto the campus, Xing said, according to the news agency.

The campus, where Olympic and Paralympics table tennis events will be held, is a huge tourist attraction, and every summer, thousands of parents go there to try to motivate their children to do well in their studies, Xinhua said.

Last year, the university had to take measures to cope with the number of tourists, including requiring groups to book tours three days in advance, and limiting the number of sightseeing routes on the campus.

China has embarked on a wide-ranging security crackdown ahead of the Games, and has even deployed surface-to-air missile batteries near Olympic venues to defend against airborne terrorist attacks.

Authorities in the capital have also started to carry out checks in the subway, and airport security has been beefed up substantially.

The country has repeatedly warned that it faces the threat of terror attacks on the Olympics, particularly from "separatists" in its far-western Xinjiang region, which is predominantly Muslim.

Critics have accused Beijing of exaggerating or fabricating the terror threat to provide an excuse to crack down on any dissent that could embarrass China urging its time in the Olympic spotlight.