BEIJING - Education and police authorities in China have launched a campaign to wipe out sales of equipment designed for cheating in this weekend's national college entrance exam.

Some people have sold items including covert microphones to students and released misguiding information related to the exam content online, the Ministry of Education said in a statement on Wednesday.

The exam, the world's largest, takes place on June 7 and 8 this year.

Local authorities have investigated these illicit practices and busted a number of suspected criminal groups in the campaign, the ministry said, without giving more details.

It also plans to check the printing, storage and distribution of the test papers to ensure there are no leaks, and to reinforce management of invigilators to prevent cheating caused by possible cases of dereliction of duty.

There have been incidents in which invigilators, usually teaching staff from other schools, have taken bribes to allow examinees to cheat.

The ministry warned that cheating students will be stripped of the enrollment qualification this year and negligent teaching staff will be seriously punished.

The exam, known as the "gaokao," attracted nearly 9.4 million participants this year. Success in it is seen by many parents as an important way of changing their children's fate.