Chinese police have detained six people in the northwestern county of Huachi suspected of selling hi-tech devices to help students cheat in the country's make-or-break college entrance exam to be held June 7-9.

Police also confiscated 30 devices, such as receivers and earpieces, a spokesman with the Huachi Public Security Bureau of Gansu Province said Sunday.

A cheating device set could be sold for 20,000 yuan to 30,000 yuan (2,941 U.S. dollars to 4,412 U.S. dollars), the spokesman said.

By June 1 when they were detained, the suspects had acquired 28,600 yuan of down payments from 11 students, ranging from 300 yuan to 5,000 yuan each, he said.

Police are further investigating the case, he added.

In a country where a college diploma can greatly help secure a decent job, the annual college entrance exam is considered decisive in determining a student's future career opportunities.

More than 9.57 million Chinese high school students will sit the three-day exam, commonly known as "gaokao" in the country, this year.

The exam is often billed as the world's largest in terms of number of entrants.