Three days of bloody clashes between inmates in Ecuador have left 21 dead and 66 people, including five police officers, injured in the latest bout of gang violence in the country's notoriously brutal prisons, officials said Thursday.

At least five inmates died and 23 people were wounded in fresh fighting on Wednesday, the country's prison authority said. The injured included five police members.

This came after clashes on Monday and Tuesday left 16 dead and 43 injured at another Ecuadoran prison in the city of Latacunga in central Ecuador, some 300 kilometers (186 miles) northeast of the port city of Guayaquil.

Some 900 police and soldiers were deployed to put down the revolt in Guayaquil, the SNAI prison authority said on Twitter, while the interior ministry said order had been "reclaimed."

Violence in Ecuador's prisons, where drug gangs with ties to Mexican cartels vie for power, is often carried out with knives and sometimes involves beheadings.

Prison unrest has left nearly 400 inmates dead since February 2021.

In a single riot in September last year -- one of the bloodiest in Latin American history -- 122 inmates were killed at Guayas 1, the same section of the Guayaquil prison where Wednesday's clashes occurred.

Police said Wednesday's injured included five of their own who were attacked "with firearms while intervening to restore order."

Some of the inmates were injured with "explosives," which also caused structural damage to the facility, said the prison authority.

The clashes involved inmates from three of the 12 sections of Guayas 1, which houses nearly 7,000 prisoners as part of a larger complex that holds more than 13,000.

The Guayaquil prison is 20 percent overpopulated.

Torture centers

The SNAI sent in tactical units to re-establish order after Monday's riot at Latacunga prison, which houses 4,300 inmates and is one of the largest in the country.

On Tuesday, further clashes broke out.

Following Monday's massacre, worried relatives waited outside the prison desperate for news on the fate of their loved ones.

"I'm looking for my brother Carlos Bravo. I got here at 6:00 am," one tearful woman who did not give her name told AFP Tuesday.

After the violence, 135 Latacunga inmates were transferred to other facilities as a "security measure," according to the SNAI.

In the past, such transfers have caused further problems as the gangsters land in rival territory.

A government committee noted in April that Ecuadoran prisons are akin to "torture centers."

Bordered by Colombia and Peru, the world's largest cocaine producers, Ecuador has gone from serving as a transit point for drug shipments to the United States and Europe to becoming a major trafficker itself.

The country seized a record 210 tons of drugs in 2021, the same year that its homicide rate almost doubled.

Overcrowding has been eased somewhat from 30 percent in 2021 through the use of pardons and parole for good behavior, but remains a major problem.

In a bid to improve prison living conditions, President Guillermo Lasso launched an inmate census in August.

In May this year, the UN High Commissioner for Human Rights expressed "deep alarm at recurring prison violence" in Ecuador, which it said underlined "the urgent need for comprehensive reform" of the justice and prison system.

The Inter-American Commission on Human Rights, for its part, has urged the Ecuadoran government to launch a "prompt, serious and impartial" investigation.