The Catholic church has launched an investigation into how two nuns, who took a vow of chastity, became pregnant after a missionary trip to Africa.

The nuns who are Africans and belong to separate orders in Sicily, were posted to the continent as part of their charity mission.

One of the nuns said to be 34 year old reportedly discovered that she was pregnant when she went to the hospital to complain about stomach pains.

According to the reports, she was transferred to a different order in Palermo to prepare for the birth of the child.

The other nun, who is a mother superior and had been caring for the elderly at an institute in Ragusa, was said to have left for Madagascar, her home country, after it was discovered that she was one-month pregnant.

Speaking on the development, a church official confirmed that an investigation has been opened into the breaching of the strict rules of chastity.