A homeless woman gave birth on a cardboard box just outside St. Peter's Square early today in near-freezing temperatures and later received an offer of one year's hospitality in a Vatican institution.

Police said the 35-year-old Romanian woman had gone into labour at about 2.30 a.m. in an Italian square just metres (yards) away from the Vatican.

An Italian policewoman, Maria Capone, helped deliver the baby, a girl, and her colleagues covered both with their jackets until an ambulance arrived.

"I think it was close to zero," Capone told Italian television.

"The baby regained colour on her face after we covered her," another policeman said.

The head of Pope's Francis' charity office, Archbishop Konrad Krajewski, later visited the woman and baby in a hospital a few blocks away and offered her one-year's free accommodation in a Church-owned apartment, the Vatican spokesman said.

He said Krajewski knew the woman and her partner, also a Romanian, because they use showers and food services the Vatican has started to help the growing number of homeless in the area.