Another suspect in the assassination of a presidential candidate in Ecuador has died in prison, the same fate that befell six other suspects to the crime at another penal facility.

The prison authority reported Saturday the killing of the Colombian suspect at the El Inca prison in Quito as President Guillermo Lasso announced the sacking of the police force's general commander, investigations chief and prisons director.

Lasso's office also said it will file a criminal complaint against the director of the Guayaquil prison, where the six prisoners were said to have died amid "disturbances."

"He has already been detained… to give his version before the prosecutor's office," the presidency said.

Authorities have not provided details on the inmate deaths, nor explained how the Quito prison failed to provide extra protection for the seventh suspect following Friday's killings.

All dead victims were arrested and detained in August over their alleged involvement in the assassination of anti-corruption crusader Fernando Villavicencio.

The centrist candidate who had been polling in second place was gunned down days ahead of the 20 August as he left a stadium where he held a campaign rally.

One suspected assassin was killed by police responding to the shooting of Villavicencio, while another six were arrested.

The suspects' deaths come just over a week before the election between leftist frontrunner Luisa Gonzalez and challenger Daniel Noboa.

The winner of the 15 October vote will succeed Lasso, who called snap polls to avoid possible impeachment for embezzlement.