A statutory inquiry is to be set up by the Irish Government into state sanctioned, religious-run institutions used to house pregnant mothers.

The special commission of investigation will examine the high mortality rates at Mother and Baby homes across several decades of the 20th century, the burial practices at these sites and also secret and illegal adoptions and vaccine trials on children.

It is thought about 35,000 unmarried mothers spent time in one of 10 homes run by religious orders in Ireland.

The inquiry has been ordered after massive national and international focus on the story of one home, run by the Sisters of the Bon Secours in Tuam, Co Galway, where the remains of 796 infants are believed to be buried. Some lie in the remnants of what was once a concrete septic tank on the grounds of the home.

Children's Minister Charlie Flanagan said it was time to shed light on another dark period in Irish history.

The investigation will follow the exposure of horrific levels of clerical abuse in dioceses around Ireland by priests; the abuse over several decades of children in institutions, orphanages, industrial schools; and the use of state-sanctioned, church-run Magdalene laundries for destitute women.

"I believe that Tuam should not be looked at in isolation because over the last century we have had Mother and Baby homes right up and down the country," Mr Flanagan said.

"It's absolutely essential that we establish the facts and in this regard it's a time for sensitivity rather than sensationalism, a time for seeking the truth rather than indulging in speculation."

Mr Flanagan told RTE Radio the inquiry will be formally established after a cross departmental review of files in relation to Mother and Baby homes reports back to Government by the end of the month.

Outside of Tuam three other Mother and Baby homes have little angels plots believed to hold the remains of another 3,200 babies and infants. They are Sean Ross Abbey, Tipperary - where the story of Philomena Lee began - Bessborough, Co Cork, and Castlepollard, Co Westmeath.

Infant mortality rates ranged from 30-50% in some of the homes in the 1930s and 1940s.