Mexican authorities say they have seven people in custody in connection with the May 26 abduction of 12 patrons from a capital bar and their subsequent murder.

Four suspects have been formally charged, Mexico City district attorney Rodolfo Rios told a press conference.

At least 10 of the people snatched from the Heaven bar in Mexico City's upscale Zona Rosa district were among the 13 bodies discovered last week in a clandestine grave near the capital.

Forensic personnel are still working to identify the other three skeletons unearthed on the La Mesa ranch in the municipality of Tlalmanalco.

The grave - covered with cement, asbestos and lime - was discovered during a unrelated firearms investigation by federal authorities.

The mass abduction and murder was carried out in reprisal for the May 24 killing of Horacio Vite Angel, a reputed member of the La Union de Insurgentes drug gang, by the rival La Union de Tepito group, Rios said.

One of the people taken from the bar and killed, 16-year-old Jerzy Ortiz, was the son of Jorge "El Tanque" Ortiz Reyes, the jailed boss of La Union de Tepito, officials said earlier.

Victor Manuel Aguilera Garcia, who was arrested last Thursday after investigators identified him from the bar's security tapes, confessed to his involvement and led authorities to the other suspects, Rios said.

Asked whether any of the Heaven bar victims were implicated in the homicide that ostensibly provoked the abduction, the prosecutor said it was too soon to draw any conclusions on that score.

One of the suspects accused as an accessory to the kidnapping is a partner in the bar, Rios said. EFE