Spain's Prime Minister Mariano Rajoy admitted Thursday he made a mistake in trusting a party colleague at the center of a major corruption scandal but rejected repeated calls to resign.

Rajoy, 58, came out fighting in parliament, pouring scorn on calls for him to step down over allegations surrounding his ruling Popular Party's disgraced former treasurer, Luis Barcenas.

Spanish King Juan Carlos's daughter Cristina is moving with her children to work in Switzerland, her employer said, two months after a court named her in a corruption case against her husband.

The scandal has plunged Juan Carlos's family into its worst popularity crisis in his nearly four-decade reign.

The driver of a train that derailed in Spain killing 79 people was on the phone to a coworker at the time of the accident, while the train was racing at nearly twice the speed limit, investigators said Tuesday.

The train's two data recording "black boxes" showed that moments before the crash the train was travelling at 192 kilometers (119 miles) per hour, said the Superior Court of Justice of Galicia, which is leading the investigation.

Spain mourned the 79 people killed in its worst train disaster in decades with a solemn memorial service on Monday attended by hundreds in the pilgrimage city of Santiago de Compostela.

The heir to the Spanish crown Prince Felipe, his wife Princess Letizia and his eldest sister Elena, dressed all in black, walked solemnly down the aisle of the city's towering cathedral.

Spain has eased intensive checks on the Gibraltar border that caused delays to car traffic but Britain will be "closely monitoring" the situation, Prime Minister David Cameron's spokesman said Monday.

London has raised concerns with Madrid after Gibraltar's government said vehicles leaving the British-held territory on Spain's southern tip had been made since Friday to wait nearly six hours to get through new security inspections.

Spain's interior minister announced Saturday that the driver whose speeding train crashed, killing 78 people, is now being held on suspicion of negligent homicide.

Minister of Interior Jorge Fernandez Diaz announced the step against Francisco Jose Garzon Amo, who previously had been detained on suspicion of recklessness following Wednesday's crash in Santiago de Compostela.

Tired and drained after supporting families of the victims of the train crash in Spain that killed at least 78 people, psychologist Jorge Carballido is amazed by the "human strength" on show.

"The resistance they have, the strength they have," said the 40-year-old, his voice breaking, standing in front of a municipal building in the northern city of Santiago de Compostela.

U.S. President Barack Obama expressed dismay Thursday at the train crash in Spain that left at least 80 people dead, including one American.

"Michelle and I were shocked and saddened by the news of yesterday's tragic train derailment in Santiago de Compostela, Spain," he said.

Spain will observe three days of mourning for the victims of a train crash that killed at least 78 passengers and injured more than 140, Prime Minister Mariano Rajoy said Thursday.

"Today I will sign a decree declaring three days of official mourning in all of Spain," he told reporters in his hometown of Santiago de Compostela where the disaster occurred on Wednesday.

Archaeologists said Wednesday they have found a flint blade dating back 1.4 million years in the caves of Atapuerca in Spain, the earliest sign of a human presence at the site.

The three-centimeter (1.2-inch) blade was found in the so-called Elephant Chasm cave where in 2007 researchers found a human finger and jawbone dating back 1.2 million years -- considered the remains of the "oldest European" ever found.