BEIJING -- Explosions rocked China's top two universities in Beijing on Tuesday, injuring at least nine people, university authorities said.

The explosions came a week before the annual session of the National People's Congress, or Parliament, amid tightened police security in and around the capital, Reuters reported.

A blast hit a cafeteria at Qinghua University shortly before noon, injuring six people, a university official said by telephone.

At nearby Peking University, an explosion rocked a canteen kitchen at around 01:30 P.M. (0530 GMT), slightly injuring three people, a university spokeswoman told Reuters.

Police had cordoned off the areas and were investigating.

The three injured at Peking University, all cooks, were rushed to the campus clinic, a doctor said, adding that they had suffered cuts from broken glass.

"The explosion was very loud. Shocked cafeteria employees screamed," the doctor said.

The official Xinhua News Agency said earlier the explosion at Qinghua University filled the cafeteria with "the smell of gunpowder" but called it an "accident".

About 40 people were having lunch at the Qinghua University cafeteria at the time and were evacuated, Xinhua said.

A Foreign Ministry spokesman said police were investigating the Qinghua explosion but that he had not heard of the blast at Peking University.

Qinghua University, also known as Tsinghua, is the alma mater of Premier Zhu Rongji and Communist Party Chief Hu Jintao, who is tipped to take over the presidency from Jiang Zemin at the annual session of Parliament in March.

"I eat lunch at the cafeteria often. If the explosion happened earlier, the consequences would have been drastic," said a Peking University student who would only give his surname Wang.