The Mexican Attorney General's Office says 111 of its officials have been charged with fraud, embezzlement and abuse of power and 192 others have been fired for botching investigations.
Inspector General Cesar Alejandro Chavez says dozens of other agents and prosecutors are being investigated on criminal charges.
The fired officials are accused of carrying out illegal raids, receiving bribes and freeing suspects.
Chavez says it is the largest purge at the agency since President Felipe Calderon took office in December 2006, declaring a war on drug cartels.
The sweep started in April when Marisela Morales was appointed attorney general promising to fight internal corruption. She formerly was the top organized crime prosecutor.