SYDNEY: A woman imprisoned for 20 years over the deaths of her four children was pardoned by New South Wales state on Monday after a judicial review found there was reasonable doubt about the original convictions.

Kathleen Megan Folbigg was convicted in 2003 for the murder of her three children and manslaughter of her fourth. Folbigg maintained her innocence and said the children had died of natural causes.

An initial inquiry in 2019 found the evidence reinforced Folbigg's guilt. However a second inquiry led by former chief justice Thomas Bathurst revisited her convictions in 2022 after new evidence suggested two of the children had a genetic mutation that could have caused their deaths.

New South Wales state Attorney General Michael Daley pardoned Folbigg on Monday after summary findings from the Bathurst inquiry found reasonable doubt for each conviction.

"The result today is confirmation that our judicial system is capable of delivering justice, and demonstrates that the rule of law is an important underpinning of our democratic system," said Daley.

"Given all that has happened over the last 20 years, it is impossible not to feel sympathy for Kathleen and Craig Folbigg."

Daley said the unconditional pardon would allow Folbigg to walk free but would not quash her convictions.

In a memo to the Attorney General, Bathurst said there was a reasonable possibility three of the children died from natural causes, two due to a genetic mutation known as CALM2-G114R and one because of an underlying neurogenic disorder.

Such doubts then undermined the Crown's case in relation to the manslaughter of her fourth child, Bathurst added.

"Further, I am unable to accept the proposition that the evidence establishes that Ms Folbigg was anything but a caring mother for her children," he said.