The fate of a four-year-old Brisbane girl remains unclear as her South Korean mother is being forced to leave the country.

Eunsil Park has lived in Brisbane for eight years and had a child with her former Australian partner in 2009.

Her daughter Ari Illingworth, is an Australian citizen.

When Ms Park's relationship broke down, her fiancee visa ended.

She applied for permanent residency but her request has been denied by Immigration Minister Scott Morrison.

"I couldn't believe it, what they had decided," Ms Park said.

A letter from the Immigration Minister to Ms Park states it would not be in the public interest to intervene and grant her residency.

Ms Park has until Monday to buy a plane ticket out of the country.

Her daughter's Australian grandfather, Mark Illingworth, says he is angry the Federal Government is allowing this to happen.

He says he is worried about his four-year-old granddaughter moving to South Korea.

"I keep saying to people what are the rights of the child? There are circumstances that they need to get a little bit of heart back into the role," he said.

"They seem to want to do everything they can overseas for a citizen, but they won't look after a five-year-old citizen, a beautiful little girl here in this country."

A spokesman for Mr Morrison says he will not comment on the case.

Editor's note: This story has been amended to make clear the circumstances surrounding Ms Park and her daughter.