"There are 40 hurt, all mild, none seriously," security secretary Sergio Berni told reporters.

The accident occurred in the city of Temperley but both trains were travelling at low speeds at the time.

Initial investigations suggested that the driver of the passenger train ignored at least one stop sign, the Argentine transport ministry said in a statement.

In 2012, a train crash left more than 50 dead and over 700 injured at Once terminus, also in Buenos Aires.