Nuns belonging to the Missionary Sisters of Charity order founded by Mother Teresa of Calcutta have been attacked and beaten in their home in Mar del Plata, Argentina.

The attack also saw the criminals desecrate the tabernacle of the nuns' chapel and steal a small amount of money, according to the Fides news agency.

The order has worked in Mar del Plata for 20 years. It is active in helping terminally ill AIDS patients and in other humanitarian work in the area.

Mar del Plata is a major fishing port and seaside resort in the southeast part of Buenos Aires Province, the seventh largest city in Argentina.

Mother Teresa founded her Missionaries of Charity in 1950. It now comprises more than 4,500 religious sisters who take vows not only of poverty, chastity and obedience but promise to give "wholehearted free service to the poorest of the poor".

The order has 19 homes in Calcutta but works throughout the world providing AIDS care, refugee support, homes for people with leprosy, and support for alcoholic and homeless people.

Mother Teresa herself, orginally from Albania, died in 1997. A controversial figure during her lifetime, she is to be formally declared a saint by Pope Francis on September 4.