The Spanish government said Wednesday it was hunting for the authors of malicious jokes on Twitter about the victims of the air crash in the French Alps.

"If they were all Germans and Catalans, what is the tragedy?" wrote one user, flagging the Tweet with the hashtag #Germanwings.

A plane operated by the budget carrier of Germany's Lufthansa crashed in a remote area of the French Alps Tuesday, killing all 150 on board in France's worst aviation disaster in decades.

With the cause of the accident a complete mystery, authorities recovered a black box from the Airbus A320 at the crash site, where rescue efforts were being hampered by the mountainous terrain.

Spain's King Felipe VI Thursday praised the merits of unity in his first speech in Catalonia since the wealthy northwest region held a symbolic vote on independence.

"We cannot allow weakening or division as the world moves towards greater integration, reflecting the increased interdependence that defines our societies and economies," the monarch said in his speech to Catalan business leaders in Barcelona.

Spanish Prime Minister Mariano Rajoy said in Catalonia Saturday that he would not allow any challenge to national unity, on his first visit to the region since its symbolic vote on independence.

"I will not allow challenges to the unity of Spain," Rajoy said in a speech to supporters of his conservative Popular Party in the region's main city of Barcelona.

Knocking on neighbors' doors in central Barcelona, 46-year-old engineer Jaime Gutierrez and retiree Toni Vinas, 74, are out canvassing their fellow Catalans to vote Yes to independence from Spain.

Going door to door in the neighborhood around the city's Sagrada Familia Cathedral, they are just two in an army of volunteers mobilized for the ballots in the Catalonia region on Sunday in defiance of legal challenges by Madrid.

Catalonia's president on Saturday formally called a referendum to decide whether Spain's richest region should be independent, in a defiant move immediately rejected by Madrid as anti-constitutional.

Shortly after Artur Mas set the vote for November 9, the Spanish government said the referendum would not be allowed to take place, with Deputy Prime Minister Soraya Saenz de Santamaria warning no one "was above the national will of the Spanish people."

Barcelona's vice-president in charge of finances says it had a record income of 530 million euros ($711 million) over the past year, and managed a profit of 41 million euros ($55 million).

Javier Faus presented the club's financial report for 2013-2014 on Tuesday, and said it made money on it operations, year-to-year, and reduced its net debt.

Spain may have been embarrassingly dethroned as World Cup holders, but Real Madrid and Barcelona are still champions at making money after they were named as the world's two richest sports franchises.

For the second successive year, Forbes business magazine tagged European champions Real Madrid, where Cristiano Ronaldo plays, as the number one sports team with a value of $3.44 billion.

Thirty people were arrested and 14 others hurt when police clashed with stone-throwing youths in a third night of riots sparked by a squat eviction in Barcelona, officials said Thursday.

Hooded youths burned bins, broke windows and hurled bottles and stones when police charged them after some 2,000 people gathered for a protest on Wednesday night, an Agence France Presse reporter saw.

Spanish police charged at youths who attacked their vans and lit fires in a second night of riots over the demolition of a popular Barcelona squat, officials said Wednesday.

Police have arrested eight people in clashes that erupted after squatters were cleared from "Can Vies", a public building occupied for 17 years by left-wing radicals in the northeastern city.