The federal police force in Mexico has sacked almost 10% of its officers this year for corruption, incompetence or links to criminals.
Commissioner Facundo Rosas said 3,200 officers had been fired.
More than 1000 others were facing disciplinary action and could also lose their jobs.
Announcing the dismissals, Commissioner Rosas said none of the sacked officers would be allowed to work in police forces at local, state or federal levels.
At a news conference, he said some have been accused of having links to drug cartels in Ciudad Juarez, the country's most violent city.
The commissioner said this was only the first stage of a purge of Mexico's forces.
Soon after taking office, President Felipe Calderon launched an all-out war against the drug cartels.
In many parts of the country he has deployed the army against the traffickers despite the opposition of many of his critics.
But Mr Rosas said the federal police force was also taking part in the drugs war.
He said the ongoing purge was part of a strategy to rid the police of corruption and make its 34,500 officers more reliable.
The BBC reports the war against the drug cartels has left some 25,000 people dead since Mr Calderon came to power in December 2006.