A blaze broke out on the first floor of the "Christ is Love" when a patient's mattress caught fire on Saturday [AFP]

A fire in a private drug rehabilitation centre in a densely populated area of Peru's capital city has killed at least 26 people and injured 10 others.

A police spokesperson said that the blaze broke out on the first floor of the centre when a patient's mattress caught fire on Saturday morning.

He said the deaths occurred because doors to rooms where some 40 patients were having breakfast were locked and they were stuck inside.

"So far we have information that 22 people died at the scene," said Health Ministry official Javier Correa, adding that four others died after being taken to hospitals.

He also said that at least 10 people were injured, three of whom were in "very, very serious" condition.

Peru's chief fire fighter, Antonio Zavala, said the fire was of "Dantesque proportions".

Firefighters had to punch a hole through a wall with an adjoining building to help the people trapped inside the rehabilitation center.

"We've had to use electric saws to cut through the metal bars of the doors to be able to work," Zavala said.

Television images showed relatives of center residents weeping in front of the building, located in a poor section of eastern Lima.

Gianfranco Huerta, a youth who was being treated at the centre, told local news radio station RPP that he jumped from the second floor of the center to escape the fire.

Huerto said that he was having breakfast when he saw the flames coming from the first floor.

"The doors were locked, there was no way to get out," he said. "I could just see smoke and hear screams."

Paramedics and firefighters were on the scene in Lima's San Juan de Lurigancho neighbourhood, and the injured were being taken to hospitals, the Health Ministry said.

Local media reported that the drug and alcohol rehabilitation centre, called "God is Love," sought to treat addicts through Biblical teachings.

No representative of the center could be immediately reached for comment.

Peru's fire fighters are notoriously underfunded. All the South American country's firefighters are volunteer and the annual firefighting budget for the entire country is $19m.