PRIME Minister Julia Gillard will formally apologise to victims of past forced adoption practices during a ceremony next month.

From the 1950s to the 1970s, about 150,000 unwed Australian mothers had their babies removed by churches and adoption agencies.

In some cases, women were tricked into signing adoption papers while shackled to hospital beds.

The Federal Government will offer a national apology to those mothers and children on March 21, when the parliament sits in the Great Hall of Parliament House, which has room to seat 800 people.