BUENOS AIRES (AFP) - Three relatives of Pope Francis, two great nephews and their mother, have been killed in a traffic accident in Argentina, the police said on Tuesday.

The dead include a baby of eight months and a two-year-old toddler, police commissioner Carina Ferreyra said.

Their father, the Pope's nephew Horacio Bergoglio, is in serious condition, she told AFP. He is the son of Alberto, the Pope's late brother. He has been hospitalised with multiple injuries. Official details of his condition have not been released.

The accident happened after midnight in the central province of Cordoba when the family was traveling on a highway, some 550km north-west of the capital Buenos Aires, near the city of James Craik. For reasons that are under investigation, the car hit a truck from behind.