WASHINGTON — The US has offered a $5m (£4.1m) reward for details leading to the arrest of the "masterminds" who orchestrated the assassination of an Ecuadorean presidential candidate.

Fernando Villavicencio, who campaigned against corruption, was shot dead at a rally in August.

Organized crime was behind the killing, Ecuador's president said at the time.

The US also offered a $1m (£800,000) reward for information on any leaders in the gang responsible for his death.

"The United States will continue to support the people of Ecuador and work to bring to justice individuals who seek to undermine democratic processes through violent crime," Secretary of State Antony Blinken, who announced the reward, said on Thursday.

The investigation was being supported by the FBI, and the reward showed Washington's commitment to fighting organized crime, Blinken added.

Villavicencio's election campaign had focused on tackling corruption and criminal gangs, and he was one of the few candidates to allege links between organized crime and government officials in Ecuador.

A serving congressman and former journalist, he had condemned what he said was the lenient approach to the gangs, saying that were he to come to power, there would be a crackdown.

Just weeks before he was killed, the mayor of the Ecuadorian city of Manta was shot dead. In February, the mayor of Puerto López was murdered while touring his city.

But the shooting of a presidential candidate at a public event in the capital was the most brazen attack so far and a testimony to the strength of the gangs in Ecuador.

Ecuador has historically been a relatively safe and stable country in Latin America, but crime has shot up in recent years, fueled by the growing presence of Colombian and Mexican drug cartels, which have infiltrated local criminal gangs.

Police in the country say they have so far detained six Colombian nationals in relation to Villavicencio's death, but are still searching for other suspects.

This is not the first time the US has offered rewards for information on crimes committed in other countries. This week it offered a reward of up to $5m (£4.1m) to help find Abukar Ali Adan, the deputy leader of the Somalia-based militant group, al-Shabaab.

Last year, the US Drug Enforcement Agency also offered the same monetary reward for information leading to the arrest of top members of the Irish Kinahan organized crime group. — BBC