A son of Mexican drug lord Joaquin "El Chapo" Guzman was among a group of people kidnapped from a restaurant in the Pacific Mexican tourist resort of Puerto Vallarta this week, the state's Attorney-General says.

A group of six people, suspected to be members of Guzman's feared Sinaloa Cartel, were abducted by a group of armed men from the restaurant in the heart of the resort early on Monday.

Seven gunmen in pickup trucks abducted the victims around dawn on Monday in what investigators have called a likely settling of scores between rival drug cartels.

Authorities initially said 10 to 12 people had been kidnapped, but reduced the number to six after analysing security camera footage and interviewing witnesses.

Jalisco Attorney-General Eduardo Almaguer told a news conference that one of Guzman's son, Jesus Alfredo Guzman, was among those abducted.

"Jesus Alfredo Guzman Salazar, 29, is the son of Joaquin (Guzman) Loera, this has been confirmed" he said.

"The person ... has been identified through [inspections of] vehicles and by security agencies, as well as through expert opinions."

He said Alfredo Guzman was one of the four people who had so far been identified among six abducted.

Earlier reports had said it was believed another son, Ivan "El Chapito" (Little Chapo) Guzman, was among taken.

Their father is now in a maximum security federal prison in the northern city of Ciudad Juarez, after staging a spectacular jailbreak last year only to be recaptured in January.

The chief prosecutor said only fake identity documents had been found at the scene of Monday's kidnapping at the La Leche restaurant.

He said initial evidence suggested a rival cartel called Jalisco New Generation was behind the abduction.

Jalisco New Generation emerged in Puerto Vallarta in 2010 after the death of the local boss of the Sinaloa cartel, Ignacio '"Nacho" Coronel.

It has become one of violence-plagued Mexico's most powerful drug gangs in recent months by defying the authorities with a series of brazen attacks and ambushes.

In 2008, another of Guzman's sons, Edgar, was murdered in a Sinaloan shopping mall by hitmen hired by the Beltran Leyva drug cartel, sparking a war with the Sinaloa Cartel.

AFP/Reuters