Train drivers in Spain are due to begin a three-day nationwide strike on Monday in protest of what they say is a lack of safety guarantees on the country's rail system.

The action follows two fatal train crashes in January, one in Adamuz in the country's southern region which killed 46 people, and the second just two days later near Barcelona where a train driver died and dozens were injured.

The accidents have caused severe disruption for travellers and cast doubt on Spain's much-vaunted rail system.

Semaf, the train drivers' union, are demanding the hiring of more staff and increased investment and maintenance in what it has described as "the constant deterioration of the rail network".

Following the two collisions, subsequent safety checks also revealed faults and maintenance issues on a number of routes.

Spain's Prime Minister Pedro Sánchez is due to be grilled in parliament later this week about the failures in the rail system.

A preliminary report by rail accident investigation commission CIAF has found that grooves found on the wheels of the derailed train and three earlier trains suggests that a fracture in the track occurred before the train went over it.

Rail officials believe the wall collapsed as the train was passing, striking the driver's cab first and then causing considerable damage to the first carriage of the train in which most of the injured passengers were travelling.

Semaf has previously said the collisions represent "a turning point in demanding that all necessary actions be taken to guarantee the safety of railway operations".

The amount of investment the rail network receives has come under particular scrutiny. The Socialist-led government has sought to dismiss such queries, pointing out that €700m (£605m) has been invested in updating the Madrid-Andalusia line in recent years, with the stretch of track where the accident took place included in that renovation.

"We're not looking at a problem of lack of maintenance, we're not looking at a problem of obsolete [infrastructure], and we're not looking at a problem of lack of investment," said Transport Minister Óscar Puente.