In a major upheaval in Mexico's troubled attorney general's office, top prosecutors in 21 of the country's 31 states and federal district have abruptly quit, officials announced Monday.

Specific reasons were not given for the en masse resignations, but they come amid a widening purge of the agency by Atty. Gen. Marisela Morales, who took office in April and has seen several high-profile drug-trafficking prosecutions fall apart.

It was not clear whether the 21 senior federal prosecutors were being forced out or were quitting in rebellion over Morales and her administration.

"The purge is fundamental within the [attorney general's office] to give citizens the results they legitimately demand," Morales said in a statement. "The Mexico of today requires that those of us in public office act with total dedication and responsibility of service."

The office announced late last month that in Morales' first 100 days on the job, 462 prosecutors and other officials had been dismissed and 111 more were facing criminal charges involving a range of infractions, including fraud, theft, abuse of power and falsification of documents. An additional 386 employees were in the process of being dismissed.

But Mexican media said the resignations announced Monday represented the single largest departure of senior-level prosecutors in memory.

Rosa Elena Torres Davila, a senior official in the attorney general's office, made Monday's announcement and said the resignations were tendered on Friday. They included the top federal prosecutors in some of Mexico's most violent states where drug traffickers have intimidated local authorities and killed thousands of people in cases that have largely gone unprosecuted. They also included the top federal prosecutor in the capital, Mexico City, which is a federal district with a status similar to that of a state.

Morales, the first woman in such a senior law enforcement position in Mexico, has been praised for a willingness to take on tough cases. But as some of those prosecutions unraveled, including efforts to try the former mayor of Tijuana on drug-related charges, she has also been accused of favoring the political will of her boss, President Felipe Calderon.

Torres Davila did not outline reasons for the prosecutors' departures, but one outgoing prosecutor, Norma Patricia Valdes of Queretaro state, told El Universal newspaper that she was leaving because a "reorganization plan" would have forced her to move to a different job and different state, which she was not willing to do.