Aristóteles Sandoval, 46, was shot in the back as he went to the bathroom at a restaurant in the city. One of his bodyguards was also shot and injured.

Mr Sandoval, who governed Jalisco from 2013 to 2018, died in hospital.

The killing is one of the most high-profile attacks on a Mexican politician in recent years.

Mr Sandoval was having dinner at the Distrito 5 restaurant in the centre of Puerto Vallarta with three other people when the attack occurred.

Investigators believe that it was meticulously planned as the gunman waited until Mr Sandoval went to the bathroom, leaving behind his two bodyguards.

He was shot in the back, but was not instantly killed. When his bodyguards tried to get him out of the restaurant and to a hospital, gunmen outside opened fire on them.

In a video uploaded to Twitter by a local TV station, dozens of shots can be heard ringing out. The bodyguards managed to drive Mr Sandoval to hospital but he died of his wounds.

Jalisco state's Attorney-General Gerardo Solís said that when police arrived at the restaurant, they found that the crime scene had been altered.

"When police arrived, restaurant staff had removed all the evidence inside. They'd practically cleaned the scene of the crime. This is going to hamper the investigation because the crime scene has literally been disturbed," Mr Solís said.

The owner of the restaurant and its staff are being questioned by police.

Mr Sandoval's time in office was overshadowed by violent attacks carried out by the Jalisco New Generation Cartel (CJNG).

Just days after he became governor, Mr Sandoval's tourism minister was ambushed and killed by gunmen believed to have links with the CJNG.

In May 2015, an army helicopter that had spotted a convoy of cars which was believed to have been protecting the CJNG leader Nemesio Oseguera Cervantes was shot down by a rocket-propelled grenade killing several of the soldiers on board.

The Jalisco New Generation Cartel is one of the most powerful in Mexico and infamous for its extreme violence.

It controls much of the trafficking of cocaine and methamphetamines in central parts of Mexico, but also engages in fuel theft, extorsion and arms trafficking.

Apart from the attacks in its power base in Jalisco state, it is also suspected of being behind the attempt to kill Mexico City's security chief, Omar García Harfuch, in June.