Mexican authorities said on Friday they have identified five bodies pulled from a mass grave as some of the 12 people kidnapped three months ago from a Mexico City bar.

Assistant attorney general Renato Sales told reporters that 13 badly decomposed bodies have been pulled from a mass grave covered with cement, lime and asbestos discovered on Thursday on a rural ranch east of Mexico City.

Officials said the remains are at federal labs, where experts are using DNA tests, and they expect to have all of them identified soon.

The young bar-goers vanished from the Heaven club at midday on 26 May, just a block from the leafy Paseo de Reforma, the capital's equivalent of the Champs-Elysees.

The bizarre disappearance resonated across the city of 9 million people because many had come to believe it was an oasis from the rampant drug violence that had led to discovery of mass graves elsewhere in the country.

Authorities set up a perimeter more than a mile from the excavation site on a hilly ranch known as La Negra, where federal police and attorney general's trucks and large white vans were seen working the operation. The private property next to Rancho La Mesa Ecological Park is walled and surrounded by oak and pine trees.

The federal attorney general's office said agents had received information about possible illegal weapons on the property and obtained a search warrant. When they started looking around, they discovered the grave.

"They found a home that looked like a safe house," Murillo Karam told reporters Thursday. "We were operating under the belief it was a weapons case."

Prosecutors have said the abductions from the Heaven bar were linked to a dispute between street gangs that control local drug sales in the capital's nightclubs and bars. They say the gangs are based in Mexico City's dangerous Tepito neighbourhood, where most of the missing lived. The families insist the missing young people were not involved in drug trafficking.

Surveillance cameras showed several cars pulling up to the bar at midday and taking the victims away. A witness who escaped told authorities that a bar manager had ordered the music turned off, told patrons that authorities were about to raid the establishment and ordered those inside to leave.

Those detained in the Heaven case include club owner Ernesto Espinosa Lobo, known as "the wolf", who has been charged with kidnapping, as well as another bar owner, a driver and a security guard. A fifth person, Jose de Jesus Carmona, 32, is under arrest pending charges and another is a fugitive.

In another element of the case that is reminiscent of cartel warfare, one of the owners of the Heaven bar, Dax Rodriguez Ledezma, fled authorities only to turn up dead, his body dumped and burned in a rural area with that of his girlfriend and another friend.