by Alonso Castillo

HERMOSILLO, MEXICO - The death toll from a fire at a day-care centre in Mexico rose to 41 children on Sunday and a dozen more were fighting for their lives in hospitals.

The northern city of Hermosillo was in mourning after a blaze spread through the ABC day-care centre there on Friday, killing babies and toddlers as parents and employees raced desperately to rescue them.

"In the past few hours three more have died," Sonora state Health Minister Raymundo Lopez told reporters. "Twelve of the 22 hospitalised children are in grave condition."

Pope Benedict said he was "deeply pained" and sent his condolences to the victims' families, saying he would pray for them.

Smoke inhalation killed many of the children, who ranged in age from a few months to three.

It was unclear where or how the fire started, although it may have broken out in a nearby warehouse in an industrial neighbourhood, the government said.

As flames blocked the centre's doorway, employees and bystanders used cars to punch holes through a wall, stumbling over unconscious infants and toddlers as they tried to find them and get them out, witnesses said.

Mexican President Felipe Calderon has ordered an investigation and visited victims on Saturday at hospitals in Hermosillo, a city of about 700,000.

"Which is your favourite Power Ranger? You look stronger than the Power Rangers," Calderon told one bedridden toddler, referring to a children's television program.

On Sunday, funerals continued, with some 20 empty graves waiting at a local cemetery.

"I'll always be your father," said one parent as weeping friends and family crowded around a small coffin.

At another ceremony, people released white balloons into the air as a coffin strewn with flowers was lowered into the ground.

Some severely burned children have been flown to specialist hospitals, including the Shriners children's hospital in Sacramento, California.

Lopez said some were suffering from respiratory problems while others with severe burns had lost body fluids, causing kidney failure.

Doctors and nurses "have worked without rest to rescue more children from death," Lopez said.

More than 140 children were in the centre when the fire broke out, the government says. The facility had passed its last government inspection in May, according to Daniel Karam, head of the Mexican agency responsible for health care and social security.

Calderon rushed medical assistance to overwhelmed medical staff in Hermosillo, 170 miles south of the US border, including air ambulances and specialists in reconstructive surgery.