Three abandoned children have been found near the skeletal remains of their nine-year-old brother at a block of flats in Texas.

Authorities said the youngsters, aged seven, 10 and 15, were discovered at an apartment complex west of downtown Houston on Sunday.

The 15-year-old reportedly said his younger brother had been dead for a year and was in the next room.

He also stated that their parents had not lived in the apartment for several months.

Harris County Sheriff Ed Gonzalez described the situation as “heartbreaking”, with the children having been living in “deplorable conditions”.

A statement on the police department’s website said: “Deputies responded to the apartment at 3530 Green Crest and discovered the skeletal remains of a small child which appeared consistent with the age provided by the 15-year-old.”

The mother of the children and her boyfriend have been found and are being interviewed by homicide investigators.

NBC News, via affiliate network KPRC, reports that the children were found during a welfare check at an apartment.

The three children may have been in the apartment for months or even a year, Sheriff Gonzalez told the station.

“I haven’t been told they were necessarily locked in, but at that age, it appears they were basically fending for each other,” he said.

Mr Gonzalez added that the three children appeared malnourished and showed signs of physical injury.

All three have been taken to hospital for treatment.