Noe Ramirez, who headed the Special Organised Crime Investigation Division, was held in an operation that has seen a number of senior officials detained.

He resigned in July as part of a shake-up by President Felipe Calderon.

The attorney general said Mr Ramirez accepted $450,000 from cartels and was offered a monthly fee for information.

The office of Attorney General Eduardo Medina Mora said Mr Ramirez had spoken to investigators voluntarily and was subsequently detained.

Mr Ramirez, who took up his post in 2006, is the highest-ranking law official yet detained in Operation Clean-up, which was launched to try to curb corruption linked to drug smuggling.

Five senior officials and two federal agents have been held in the campaign. Dozens of officials have been sacked.

Mexican authorities have also had success in arresting key members of drug cartels in recent months.

However across the country this year, more than 4,000 people have died in drug-related violence as gangs fight each other and the security forces.

The attorney general's office has particularly targeted links to the cartels of the Beltran Leyva brothers, who recently split from the Sinaloa organisation.



BBC