The prison authority in El Salvador has transferred members of the country's rival gangs into the same prison, ending the policy of segregating them.

A spokesman for the Directorate General of Prisons confirmed that following the transfer of around 1,800 gang members, criminals will be imprisoned according their level of dangerousness and not the gang they belong to.

In other words, the Mara Salvatrucha and Barrio 18 gangs will be mixed, in an effort to dismantle criminal networks operating from prisons.

El Salvador gang 18
Members of the Barrio 18 gang, displaying their allegiance with tattoos, sit handcuffed together on a bus as they arrive at the San Francisco Gotera penitentiaryJose Cabezas/Reuters
El Salvador gang 18
A member of the Barrio 18 gang waits to be admitted to the San Francisco Gotera penitentiary after being transferred from Izalco jailJose Cabezas/Reuters
El Salvador gang 18
Members of the Barrio 18 gang, handcuffed together, are made to run upon their arrival at the San Francisco Gotera penitentiaryJose Cabezas/Reuters
El Salvador gang 18
Members of the Barrio 18 gang are transfered from Izalco jail to San Francisco Gotera in a effort to curb gang violenceJose Cabezas/Reuters

At least nine members of the gang Barrio 18 were killed in El Salvador on Saturday 18 April in a confrontation with the army.

El Salvador gang 18
Salvadoran soldiers and policemen secure a crime scene in the town of Zacatecoluca, where at least nine members of the gang Barrio 18 were killed in a confrontation with the armyReuters

Violence in El Salvador has increased over the past year. In 2012, El Salvador's two main gangs, Barrio 18 (18th Street) and Mara Salvatrucha (MS-13), agreed to a historic but controversial truce that temporarily caused the homicide rate to drop sharply. That truce broke down last year, and violence has surged.

El Salvador had more homicides in March than any other single month in a decade, as gangs battle for control of drug trafficking and extortion operations. According to data from National Civil Police, 481 people were killed in March, a rate of more than 15 a day.

Both gangs have killed thousands of people since their creation in 1960s and 1980s and also have links with some of the biggest drug cartels in Mexico, such as Los Zetas and Sinaloa.

Members of both gangs distinguish themselves by covering the body and also often the face in gang tattoos. They also have their own sign language.

Barrio 18 was formed in Los Angeles in the 1960s and is thought to have about 35,000 members in the US, Canada and Central America.

El Salvador gang 18
A prisoner shows off his Barrio 18 tattoos at the Izalco prison in May 2013Ulises Rodriguez/Reuters
El Salvador gang 18
A jailed gang member with "18" tattooed on his face poses for a photograph at the Izalco prison in May 2013Ulises Rodriguez/Reuters
El Salvador gang 18
An imprisoned member of Barrio 18 poses for a photograph at the Izalco prison, in May 2013Ulises Rodriguez/Reuters
El Salvador gang 18
A member of the 18th Street gang (Barrio 18) shows off his tattoos at the Izalco maximum security jail in Sonsonate in March 2013Ulises Rodriguez/Reuters

Mara Salvatrucha was created in Los Angeles in the 1980s by Salvadorean immigrants. It is believed to have around 70,000 members.

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A former leader of the Mara Salvatrucha or M13 gang, poses during a photo session at Comayagua jail in Honduras in February 2008Edgard Garrido/Reuters
el salvador gangs
A member of Mara Salvatrucha poses for a picture at the National Penitentiary in Tamara, Honduras, in February 2006Tomas Bravo/Reuters
El Salvador gang 18
Members of MS-13 Mara Salvatrucha flash their gang's hand sign from inside a jail cell at a police station in San Salvador in October 2012Ulises Rodriguez/Reuters