MADRID, March 24-- Spain's Deputy Prime Minister, Soraya Saenz de Santamaria confirmed in a press conference that the country would hold three days of official mourning for the 150 victims of the Germanwings flight 4U9525 which crashed in the French Alps on Tuesday morning.

The three days of mourning will begin at midnight on Tuesday, Saenz de Santamaria declared, before adding that Spain would collaborate fully with Germany and France in investigating the causes of the accident.

Spain will also send a police scientific investigation team to the crash site to help with the identification of the 150 crash victims.

It is thought that 45 Spaniards were among those who lost their lives in the crash, although the deputy prime minister said this was not a definitive number as the information could not yet be confirmed.

"We know how many Spanish surnames were on the passenger list, but we need to carry out the tasks of confirming that," she said, adding that the Spanish government could not legally publish a list of the victims' names without the airline's agreement.

Saenz de Santamaria also confirmed that the ministry of public works had set a website for families of the crash victims, while Spain's Public Works Minister, Ana Pastor had already travelled to Marseille.

Spanish Prime Minister Mariano Rajoy was scheduled to visit the area where the Airbus 320 crashed on Wednesday, while King Felipe VI and Queen Letizia of Spain returned to Madrid on Tuesday afternoon after deciding, as a result of the tragedy, to cancel their three-day state visit to France.

Before returning to Spain, Felipe VI made a joint appearance alongside French President Francois Hollande in which both gave their condolences to the families of the victims.