Mexico has fired 3,200 police officers, approximately 10% of the total police force, in a crackdown on alleged corruption and incompetence.

Mexican Police Commissioner Facundo Rosas told a news conference that the officers had failed to pass 'confidence tests' - 465 had been denounced for suspected crimes.

Another 1,485 officers from the force of 34,500 may be laid off in a second phase as investigations continue.

The massive purge is only the latest in a series of efforts to clean up Mexico's notoriously corrupt police.

The campaign has become increasingly urgent as drug violence escalates across the country.

More than 28,000 people have died in suspected drug attacks since President Felipe Calderon launched a military crackdown on organised crime in 2006. 50,000 troops have been involved in the operation.

Northeastern areas have seen a surge in violence in recent days, with incidents including the discovery of 72 massacred migrants, the murder of a mayor and five apparent bomb blasts.

The military has assumed anti-drug patrols in some spots because local police are considered unreliable.