BEIJING -- Chinese police have busted 12 criminal gangs, which produced and sold hi-tech exam cheating devices, since late May amid a reinforced crackdown against cheating ahead of national college entrance exams.

During the operation, more than 50 suspects have been captured and over 100,000 wireless cheating devices confiscated, with the total amount of money involved reaching several hundred million yuan, according to a statement released by the Ministry of Public Security Monday.

Starting from early 2018, the ministry has coordinated local authorities to conduct intensive investigations on the online sales and production network of exam cheating devices.

So far the campaign has seen more than 100 criminal groups busted and over 500 suspects arrested.

"It has ensured the security of national examinations and deterred criminals," the ministry said in the statement.

The ministry pledged a continuous crackdown on the illegal activities, in a bid to safeguard justice, equity and integrity in national exams.