Guatemala minister resigns over fire that killed 40

People take part in a protest at the Square of the Constitution in Guatemala City on March 9, 2017, following the death of 40 girls in a recent fire at a government-run children's shelter in San Jose Pinula, east of the capital

Guatemala's minister for social welfare, Carlos Rodas, offered his resignation Monday after a blaze in a government-run children's shelter killed 40 teenage girls.

In his letter to President Jimmy Morales, Rodas said he was handing in his notice in order to "contribute to the objective investigation into the tragedy."

He said he had not resigned earlier because he first needed to oversee the counseling and medical treatment of survivors at the shelter, and their transfer to other refuges.

The fire that broke out last Wednesday in the badly overcrowded Virgin of the Assumption Safe Home for children just to the east of Guatemala City killed 19 girls right away.

The other deaths came as girls taken to hospitals succumbed over subsequent days to horrific burns that had also damaged their throats and lungs.

All the victims were aged between 14 and 17. Funerals started on Friday, with some of the bodies identified through DNA samples.

Another seven girls were in critical condition. Five of them were flown to a hospital in the United States for specialized treatment.

An investigation is seeking to determine the cause and circumstances of the fire.

Initial information suggested the girls might have started the blaze themselves, setting alight mattresses to protest cruel treatment by staff in the facility, including sexual abuse.

Hundreds of demonstrators on Saturday rallied in front of Morales' presidential palace, accusing authorities of negligence and demanding punishment.

Morales said Monday he had requested that the FBI and international organizations help in the investigation, to make the process transparent.