Girl remains critical after apartment fall

A five-year-old girl remains in a critical condition more than 24 hours after she and her younger brother fell from an apartment window in Sydney's west.

The girl and a three-year-old boy, who media reports say was her brother, fell from the window of a third-storey apartment on South Terrace in Bankstown before 9am on Sunday.

Footage from the scene shows a window with a torn fly screen next to the top of a bunk bed in the apartment.

The young girl reportedly fell first and the boy then fell on top of her.

She suffered life-threatening injuries and remained in a critical condition on Monday morning, a spokeswoman from the Westmead Children's Hospital said.

The boy received minor injuries and is in a stable condition.

NSW Police say the two children were related but didn't confirm they were brother and sister.