Pope Francis' two great-nephews and their mother were killed in a car accident in Argentina during the early hours of this morning.

According to unconfirmed reports, Francis' nephew Emanuel Horacio Bergoglio was driving on the Rosario-Córdoba highway about 550 kilometres north-west of Buenos Aires with his wife and two children when their car hit a truck carrying grain.

Bergoglio is being treated at Cordoba's Pasteur de Villa Maria hospital and is said to be in a serious condition.

His wife, Valeria Carmona, and their two children, two-year-old Antonio and Jose, aged just eight months, died in the accident, according to local police commissioner Carina Ferreyra.

The incident happened around midnight local time.

Vatican spokesman Federico Lombardi confirmed that the Pope is aware of the tragic accident.

"He is deeply pained," Lombardi said, sharing that Francis has asked "all who share in his grief to unite with him in prayer."