Washington, Jul 31 (IANS): At least 973 Native American children died at US federal-operated Indian boarding schools that "forcibly confined and attempted to assimilate Indigenous children", according to a federal report.

The investigative report released by the US Department of the Interior on Tuesday urges the US government to formally apologise for the 150-year-long "deliberate and strategic actions" to assimilate the children and destroy their culture, Xinhua news agency reported.

From 1871 to 1969, the US government isolated Native children from their families and forced them to attend boarding schools, where they were deprived of their identities, language, and culture.

The department was able to identify, by name, 18,624 Native children who attended boarding school, adding that it is not a comprehensive list.

Indigenous children who died from "physical, sexual, and emotional abuse" were buried at 65 school sites in at least 74 marked and unmarked burial sites, according to the investigation.

Additional children may have died after becoming sick at school and being sent home, officials said.

It also estimates that the US government appropriated more than $23.3 billion, in inflation-adjusted dollars, during the 150 years to run such schools and associated assimilation policies.

"I think the worst part of it was at night, listening to all the other children crying themselves to sleep, crying for their parents, and just wanting to go home," The Washington Post reported, citing a boarding school survivor from Michigan.