Five prison guards were being held after a new riot broke out in a prison in Ecuador on Monday, a week after 79 inmates died in bloody gang warfare, the police chief said.

"This morning a new riot in Cotopaxi (prison) left five guards held; we're coordinating intervention," Patricio Carrillo wrote on Twitter.

A week ago, simultaneous riots broke out in four prisons, including the Cotopaxi one in the central city of Latacunga, leaving some inmates burnt and decapitated as savage fighting broke out between rival gangs.

Ecuador's human rights ombudsman described it as an "unprecedented massacre."

Authorities blamed gangs believed to be linked to organized crime in Mexico and Colombia.

President Lenin Moreno denounced the "barbarity" of the riots and said the gangs were "fighting for leadership and the trafficking of drugs throughout" Ecuador.

The four prisons account for 70 percent of Ecuador's 38,000 inmates.

Ecuador only has the capacity to hold 29,000 people in 60 prison facilities, meaning its system is around 30 percent overpopulated.

Coupled with that is a lack of guards with 1,500 employed when 4,000 are needed.

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