Fifteen children have died after a fire swept through an orphanage in Haiti run by a US Christian group, triggering renewed controversy over the proliferation of non-registered orphanages in the poorest nation in the Americas.

Two children burned to death when fire broke out at the orphanage of the Church of Bible Understanding on the outskirts of Port-au-Prince on Thursday night. Thirteen others died in hospital due to asphyxiation.

Rescue workers arrived at the scene on motorcycles and did not have bottled oxygen or the ambulances needed to transport the children to the hospital, said Jean-Francois Robenty, a civil protection official.

“They could have been saved,” he said. “We didn’t have the equipment to save their lives.”

The Scranton, Pennsylvania-based Church of Bible Understanding says on its website it started its first orphanage in Haiti nearly 40 years ago. It says its primary goal is “to spread the gospel to any and all who will receive it”.

Arielle Jeanty Villedrouin, the director of the Institute for Social Welfare, said the orphanage, which housed about 60 children, did not have state authorization to operate. Just 35 of 754 orphanages in Haiti are officially authorized, with a further 100 in the process of getting a license.

The government has closed about 160 institutions over the last five years, she said, and has barred any more from opening.

According to the Associated Press, the group lost accreditation for its homes after a series of inspections beginning in November 2012. Haitian inspectors faulted the group for overcrowding, unsanitary conditions and not having enough adequately trained staff.

The Church of Bible Understanding operates two homes for nearly 200 children in Haiti as part of a “Christian training program”, according to its most recent not-for-profit organization filing. It has operated in the country since 1977.

It identifies the homes as orphanages but it is common in Haiti for impoverished parents to place children in residential care centers.

Four in five of the about 30,000 children in Haiti’s orphanages have living parents who gave them up because they were too impoverished to look after them, according to the government.

“We take in children who are in desperate situations,” the organization says in its tax filing for 2017, the most recent year available. “Many of them were very close to death when we took them in.” The not-for-profit reported revenue of $6.6m and expenses of $2.2m for the year.