The woman who lost her arm in a lion attack at a Queensland zoo is the sister of the owner, Stephanie Robinson.

A woman in her 50s was critically injured following a lion attack at Queensland's Darling Downs Zoo on Sunday morning. As investigations continue, questions are being raised about the zoo's safety procedures and whether its animal management protocols were properly followed.

The woman in her 50s suffered a severe injury while watching keepers working in the carnivore enclosure at the Darling Downs Zoo, south of Toowoomba.