The national prisons agency Snai said prisoners had fought with guns and knives before guards managed to regain control. Latacunga is 80 km (50 miles) south of the capital Quito.

More than 400 inmates have died in prison violence since February 2021, which the government of conservative President Guillermo Lasso has attributed to gang warfare over control of territory and drug trafficking routes.

Authorities are working on identifying the bodies, officials said, while Oswaldo Coronel, governor of Cotopaxi province, which includes Latacunga, told reporters security had been restored.

Coronel said 14 of the injured had been taken to hospital.

Ecuadorean media report that those killed in the clash at Latacunga's Cotopaxi jail included an alleged drug gang boss, Leandro Norero. He was arrested in May on money-laundering charges.

The violence erupted after a census of prisoners. It came shortly after UN torture prevention experts visited Ecuador to assess its efforts to curb prison violence.

In April President Lasso declared a state of emergency in three provinces to curb gang-related violence linked to drug trafficking. A similar emergency was declared last year.

The turf wars between Ecuadorean gangs fighting for control of lucrative cocaine networks have put a huge strain on the under-resourced and overcrowded prison system.

The worst prison clash was in the port city of Guayaquil in September last year, when more than 120 inmates died.

Last year Ecuador's police seized a record 190 tonnes of drugs, mostly cocaine.

There are about 33,500 people in Ecuador’s prisons, which are 11.3 percent beyond maximum capacity, according to official figures.