Five individuals and corporate entities allegedly responsible for catastrophically gassing two newborn babies at Bankstown-Lidcombe Hospital in 2016 will face charges brought by Safe Work NSW.

Days-old babies John Ghanem and Amelia Khan ingested nitrous oxide - commonly known as "happy gas" but toxic to babies - when it was incorrectly connected to the oxygen outlet in the resuscitation unit of one of the hospital's operating theatres.

Amelia Khan suffered brain damage and is being fed through a tube.

John died, while Amelia left hospital suffering life-altering brain damage.

Safe Work NSW is believed to be looking to prosecute the South West Local Health District, gas installer Christopher Turner and his employer, medical supply company BOC, which supplied the gas to the hospital.