Corruption and bribery cases regularly make headlines in Thailand, but it is rare for so many public officials to be affected.
The scandal began in June, when investigators said they had concluded that officials accepted bribes of up to 800,000 baht (US$23,847) to electronically alter candidates' results to allow them to pass mandatory exams for government appointments or promotions.
Police found irregularities in the results of 5,814 civil servants who had taken these exams, interior ministry official Unsit Sampuntharat told reporters on Thursday.
He said they could be suspended pending a committee decision as early as Friday.
"The damage is enormous, and it is unfair to those who obtained their positions honestly," Unsit said.
