An investigation is underway after it was revealed a university has been paying college students to grade national college entrance exam papers, Beijing Times reported.

The education bureau of Shaanxi province on Thursday suspended 240 undergraduates of Xi'an International Studies Universities from marking the province's national college entrance exam, or gaokao.

The education bureau said on its website said using students to grade gaokao was against the rules and illegal.

Papers already marked will be reviewed by qualified staff to ensure no mistakes. And relevant organizers will face consequences, according to the bureau.

The university has been using undergraduates to mark papers for five years and asked students to keep the policy secret, according to Thursday's Guangdong-based Xinkuaibao Newspaper.

A professor with Huazhong University of Science and Technology revealed that some teachers are averse to paper grading due to the low pay and high intensity of the work.