More than 100 police were lead away in handcuffs after the raid by their colleagues in the judicial police.

Mexico City's attorney general, Samuel del Villar, said the arrests were an unprecedented step in the battle against corruption in the nation's police forces.

Officers were armed with automaitic rifles

"This is part of a house cleaning," added Mexico City police chief Alejandro Gertz. "We will continue to clean our ranks."

The round-up began when some 200 police were told to report to a training course unarmed.

Local media reports said the suspects were told to wear police-issue blue tracksuits.

Members of the judicial police detective force, wearing ski masks and armed with automatic rifles, then charged in and arrested anyone wearing the tracksuits.

Mr del Villar said 44 people, 35 officers and nine private security guards, were held after their names were checked against lists of arrest warrants.

Twenty of the officers belong to Mexico City's auxiliary police force which performs most day-to-day police functions. The other 15 are members of the capital's banking police.

Mr del Villar: The crackdown will continue

Charges against them include rape, murder, robbery, abuse of authority and aggravated assault.

Mr del Villar credited Mexico City Mayor Cuauhtemoc Cardenas, who took office a year ago, with the first serious attempt to clean up Mexico's police forces.

Some arrest warrants were still outsanding from 1991.

Mr Cardenas has pledged to improve law enforcement and crack down on police complicity with crime.

Appalling reputation

Police corruption has also prompted President Ernesto Zedillo to propose the creation of a national force with higher standards than local police agencies.

But opposition lawmakers have suggested that the new national police would be just as likely to become corrupt, and could be used for political purposes.

Monday's mass arrests were the latest in a city where the police force suffers from a dismal reputation among the 20 million residents.

In July, 15 officers were arrested as suspects in the kidnapping and gang rape of three teenagers.

In October, the Norwegian Embassy said a gang of city policemen forced a Norwegian tourist into a patrol car, robbed him at gunpoint, before dumping him on a highway locked in the trunk of another vehicle.