Nearly 30 prisoners were killed in a battle between inmates equipped with firearms and grenades at a prison in Ecuador's largest city Tuesday, officials said.

It was the latest in a series of deadly prison clashes between rival drug gangs that have killed over 100 inmates this year.

Ecuador's attorney general's office said on Twitter it was investigating the deaths of 29 convicts at the Litoral Penitentiary in the city of Guayaquil, including six who were beheaded.

Officials gave conflicting statements on how many inmates were wounded, with the attorney general's office saying 42 while the national prison bureau earlier put that number at 48.

President Guillermo Lasso retweeted an announcement from the prison bureau saying order "has been restored at the Littoral Penitentiary after the Tuesday incidents."

Ecuador's prison system has become a battleground between prisoners linked to Mexican drug gangs -- mainly the Sinaloa and Jalisco New Generation cartels.

Guayaquil, Ecuador's main port city, is a major hub for shipping South American cocaine north, especially to the United States.

Last week police confiscated two pistols, a revolver, some 500 rounds of ammunition, a hand grenade, several knives, two sticks of dynamite and homemade explosives at one of the city's prisons.

Two weeks ago, Guayaquil's Prison Number 4 was attacked by drones, part of "a war between international cartels," prison authorities said. There were no casualties in the attack.

Ecuador's prison system has about 60 facilities designed for 29,000 inmates, but is burdened by overcrowding and staffing shortages.

The country's human rights ombudsman said there were 103 killings in prisons in 2020.

27 inmates died in prison riots in two jails in July, in an incident that forced the government to declare a state of emergency.