Authorities in El Salvador have arrested more than 75 alleged members and associates of the notorious Mara Salvatrucha gang in a series of raids that they claim attack the financial networks of the group's leaders for the first time.

Police said they froze 30 bank accounts and seized numerous businesses, buses, and brothels controlled by the gang known as the MS-13.

The operation — dubbed Jaque, the Spanish word for putting an opponent in check in a chess game — began Wednesday night. It is the latest development in a major government crackdown on the street gangs that have terrorized many poor urban areas across the country.

The long-running war between the MS-13 and the rival Barrio 18 gang has caused the murder rate to spike horrifically in the tiny Central American nation, turning El Salvador into the world's deadliest peacetime nation in 2015. The killing broke new records in early 2016 in response to a crackdown that many human rights activists claim has made things worse. However, the murder rate has dropped dramatically in recent months.

"Of the eight main ringleaders, we have captured five, including their treasurer," El Salvador's Attorney General Douglas Meléndez told reporters on Thursday.

Meléndez said that as well as managing the gang's accounts, Marvin Adaly Ramos Quintanilla worked as an evangelical preacher, which was really a front for gaining access to jailed gang leaders.

MS-13 has long ran its operations from inside Salvadoran prisons, which they often control and use as near fortresses. The government claims that its latest crackdown isolated imprisoned bosses and prompted the gangs to develop a parallel leadership outside known as "The Federation," the members of which make up the core of those arrested this week.

The authorities also sought to underscore that the latest raids expose the divide between the luxurious lifestyle enjoyed by gang bosses and the relative squalor endured by the group's foot soldiers.

"There's a clear difference between the leaders and the members of the gangs. The majority of the gang members live in very depressing and deplorable places," Meléndez said. "The ringleaders have been profiting from the whole gang structure."

Local news website El Faro, which has often criticized government anti-gang efforts as heavy-handed, highlighted the novelty of a police strategy that is apparently aimed at fueling resentment among rank and file gang members.

El Faro, whose award-winning reporters have delved deep into gang culture, said the leadership often relies on transmitting the image of "horizontality," with bosses often preferring to call themselves spokesmen.

"This development is potentially a bombshell inside of the Mara Salvatrucha," El Faro wrote in its coverage of the raids.

Human rights groups have lambasted the previous phases of the government's crackdown, which has included officials encouraging the use of lethal force, the formation of new special units aimed at taking the battle to the gangs in rural areas, and the transfer of gang leaders to new prisons.

In May, police controversially arrested 18 people for alleged ties to the gangs, some of whom had helped put together a truce four years ago that helped bring the murder rate down for a while.

Activists also object to new legislation passed in March that defines the gangs as terrorist organizations, and which they fear can be used to scare off criticism of the government.

This week's crackdown — which reportedly uses terrorism charges against some suspects — also prompted allegations that the government is using gang-related charges to round up its most outspoken critics, including Dany Romero, who claims to be a former gang member campaigning for human rights.

The British ambassador to El Salvador, Bernhard Garside, tweeted about his "concern" that the police had arrested "an ex-gang member that has worked with a British NGO for peace."

Follow Nathaniel Janowitz on Twitter: @ngjanowitz