Australia will formally apologise for the forced adoption of tens of thousands of babies born mostly to unmarried mothers between the 1950s and 1970s, the government said Wednesday.

Attorney-General Nicola Roxon said the apology for the adoptions, driven largely by religious groups in the post-war period, would be given on March 21 in Parliament House, Canberra.

"The government recognises the pain and suffering of those affected by these policies and practices," Roxon said.

"The apology will be offered on behalf of the nation as a significant step in the healing process for those affected."

The decision comes after a Senate inquiry into forced adoptions found as many as 225,000 babies were removed and called for a national apology and the establishment of "financial reparation schemes".

Scores of mothers and children gave evidence at the inquiry which looked at the forcible removal of infants between 1951 and 1975 in Australia, then a conservative and predominantly Christian nation. Given the social stigma attached to unmarried females at the time, young women who fell pregnant were often sent to stay with relatives or at group houses run by churches or other religious organisations.

Babies were often signed away for adoption before they were born. The inquiry found women were pressured to consent, signatures were sometimes fraudulently obtained, and adoption was presented as inevitable.

Women later struggled to reunite with their children. In many cases adopted babies had their birth certificates issued in their adoptive parents' names, on the grounds that a "clean break" was best for all parties.

Roxon said these practices "resulted in profound feelings of sadness and loss, not only for the mothers who had their children taken, but their children, fathers and countless other family members".

"We hope that this national apology will assist in recognising the hurt and help families to heal," she said.