A candidate in Ecuador's upcoming presidential election who campaigned against corruption and gangs has been shot dead at a campaign rally.

Fernando Villavicencio, a member of the country's national assembly, was attacked as he was leaving the event in the capital, Quito.

The trade unionist, journalist, politician and maximum critic of Rafael Correa was assassinated by multiple shots fired by unknown persons as he left an electoral rally of his campaign in a central sector of Quito

He is one of the few candidates alleging links between organized crime and Ecuadorian government officials.

A criminal gang called Los Lobos (The Wolves) has claimed responsibility.

Los Lobos is the second largest gang in Ecuador with some 8,000 members, many of whom are behind bars.

The gang has been involved in a series of recent deadly prison fights, in which dozens of inmates have been brutally murdered.

In a message to the nation, the President of Ecuador, Guillermo Lasso, announced that he had decreed three days of national mourning for the assassination of presidential candidate Fernando Villavicencio, who was attacked by hitmen on the afternoon of August 9 in Quito, after a rally .

The president ordered the State of Exception throughout the country for 60 days and unfavorably the use of the Armed Forces to guarantee citizen security and the elections on August 20: "The elections are not suspended," said Lasso.