Ecuador is "seriously threatened" by drug trafficking mafias who want to "take control of all the country's prisons," President Guillermo Lasso said Monday, after the heads of the armed forces and the prison service quit following jail riots that left 68 people dead.

Lasso said a "massive operation" was underway by the police and the army in the overcrowded prison in Guayaquil, where two days of fighting between inmates armed with guns, machetes and explosives claimed dozens of lives.

The president said the country faced "one of the biggest crises in recent decades" and warned that the same drugs mafias "were bringing insecurity to our streets."

He promised joint action to end the repeated slaughters at the country's prisons.

Soldiers with rifles entered the perimeter of Guayas 1 prison, which includes several security rings, during the day, according to AFP journalists on the scene. But by the evening they had not yet entered the wings where the prisoners live, according to a military source.

The 1,000 police and soldiers entered Guayas 1 "to control access and the external and internal perimeter", Lasso said.

Lasso was speaking after accepting the resignations of Vice Admiral Jorge Cabrera, head of the joint command, and Bolivar Garzon, head of the SNAI prisons agency.

Social media posts showed gruesome images of prisoners beating and setting fire to bloodied bodies in an eruption the government labeled "barbaric."

"The country is under attack, under an international mafia of drug cartels," presidential spokesman Carlos Jijon told the Teleamazonas network.

This year, Ecuador's violent, decrepit and overcrowded prisons have seen some of the worst rioting in the history of Latin American penitentiaries.

More than 320 inmates have been killed so far in 2021, and the latest riot happened despite a state of emergency enforced in Ecuador's prison system after even deadlier fighting in September.

Jijon said many of the victims of the latest riot Friday and Saturday were "incinerated, mutilated" and many of the bodies "unrecognizable."

Lasso appointed army commander General Orlando Fuel as the new head of the joint command. Marlo Brito, who was head of the Center for Strategic Intelligence (CIES), took over from Garzon at the SNAI.

Another riot in the same prison in Ecuador's southwest in September left 119 dead -- making it the largest such massacre in the country's history, and one of the worst in Latin America.

Prisoners with guns

Nestled between the world's biggest cocaine producers, Colombia and Peru, Ecuador has seen a surge of violence blamed on fighting between rival drug groups.

The country of 17.7 million people is popular with traffickers because of its porous borders, a dollarized economy and major seaports for export.

Seizures of drugs, mainly cocaine, reached a record of 155 tons between January and October 2021, while street crime and warring between gang-aligned prisoners has left more than 2,000 dead so far this year.

Ecuador's murder rate rose from 7.8 per 100,000 inhabitants in 2020 to 10.6 in the first 10 months of this year, according to the government.

The prison system has 65 facilities designed for about 30,000 inmates but houses 39,000 -- 8,500 of them in Guayaquil -- Ecuador's most populous city and its main port.

The country has about 1,500 prison guards -- a shortfall of about 3,000, according to experts.

Corruption is rife, meaning that inmates can lay their hands on all sorts of contraband, including firearms and explosives.

The resultant prison riots are gruesome, with bodies often burnt, beheaded and dismembered.

Lasso declared two states of emergency after the prison unrest in September -- one for the country's jails and another to mobilize troops in the streets for 60 days in support of soldiers carrying out crime prevention patrols and searches.

The Constitutional Court subsequently placed limits on the executive intervention, barring soldiers from the inside of prisons and authorizing their mobilization among civilians for no more than 30 days.

Last week, a brand-new radar system Ecuador put up to look out for drug-transporting planes was damaged in an explosion the government said may have been a "terrorist" attack.