The gangs were charging lakhs of rupees and aiding candidates clear the online test, officials said.
"The credibility of the process was in question after the cases came to light. Therefore a decision was taken in a meeting chaired by Director General of Police OP Galhotra to cancel the ongoing process to recruit 5390 constables," Inspector Generals of Police (Headquarters) Sanjib Kumar Narzary said.
A new process was proposed to begin soon, he added.