The South Australian government is offering rewards of $1 million in each case of 18 children presumed to have been murdered, including the Beaumont siblings who disappeared in 1966.
The 13 cases involve 18 children who disappeared or were found murdered between 1966 and 2000.
Last year police made arrests in three historical murder cases, leading them to review their approach and to ask the government to increase rewards substantially.
Attorney-General John Rau said the reward for nine cases was increased from $200,000 to $1 million, while four cases previously did not have rewards.
"The gravity of these offences and the vulnerability of the child victims require the strongest-possible response," he said on Sunday.
"We owe it to the families of the victims to continue the search for those responsible for these most heinous crimes against children.
"It can take just one small piece of information that completes the puzzle for investigators or reignites the case against a particular suspect.
"We are also asking the public for information that might lead to the whereabouts of the remains of the victims of some of these acts."
Assistant Police Commissioner Paul Dickson said the rewards would hopefully encourage people to come forward with vital information that would bring some peace to the families.
The rewards are available for information leading to an arrest and conviction and for the first time, rewards will be paid for information leading to the recovering of victim remains.
The most high-profile case involves the three Beaumont children, who disappeared after visiting Glenelg Beach on Australia Day in 1966.
