Police say a Massachusetts woman robbed a nun at knifepoint and escaped with her Rosary beads.

Officers in Quincy, a suburb of Boston, said a sister at the Daughters of Mary of Nazareth convent was dressed in non-religious clothing on Sunday afternoon when a woman holding a knife approached her.

According to the arrest report, the woman said: “I'm not going to hurt you,” before trying to take a small satchel from her hand.

The nun opened the bag - displaying Rosary beads, a key and a small keepsake - to show her assailant she had no money.

The woman responded by saying: “I guess I’ll take the Rosary beads.”

Police added that the nun noticed another woman nearby acting as a lookout.

Vanessa Young has been charged with assault with a dangerous weapon (Quincy Police Department)

The victim left the area and ran straight back to the convent.

She reported the robbery and provided police with a description of the two women, who were arrested a short time later.

Crystal Young, one of two women arrested after a nun reported being robbed (Quincy Police Department)

Vanessa Young is scheduled to be appear in court on Monday on charges including assault with a dangerous weapon.