The firefighter was killed after climbing up onto the huge screen to try and stop it showing a clip from a sex film.

Alvaro Jimenez Gonzalez was trying to switch off footage of a woman using a sex toy when he lost his footing and plummeted to the ground below.

Computer hackers swapped advertisements for explicit images on the massive television in the middle of a city centre.

(Image: CEN)

Firefighters were called amidst fears that motorists on a nearby motorway would be distracted from the road by the smutty video.

The company who own the advertising board apologised to anyone who had seen the video after it began playing on a loop in Mexico city.

A spokesman for billboard owners Carteleras.com, said: "We know the discomfort of this to passersby, drivers and society in general.

"Therefore we are investigating the case with authorities."

The video began playing in the middle of the day after hackers targeted the screen, located in the San Antonio area of the Mexican capital.

Drivers on the nearby Periferico Sur motorway were surprised to see the revealing images of a woman writhing with a sex toy between her legs.

One motorist used his mobile phone to record the giant advertisement panel as it displayed the pornographic material.

(Image: CEN)

The footage went viral on social media networks and the authorities scrambled to turn off the screen.

The director of the fire brigade, Raul Esquivel, confirmed that a fireman had died.

He said: "We regret the death of our pal Alvaro Jimenez Gonzalez from the fire brigade.

(Image: CEN)

"All the support of our institution and of the government of Mexico will go to the family of our friend."

The authorities have asked owners of this kind of advertisement to improve their security measures in order to avoid a repeat of the porn hacking.

It is not the first time that hackers have targeted billboards in Mexico with pornography.

In February this year, the "menu" of a porn website was seen on an advertising board on the same motorway.

But because the hack took place at midnight, it is thought that fewer people witnessed it before it was removed.