Twelve of Europe's biggest clubs on Monday said they planned to launch a breakaway Super League, despite the threat of an international ban for them and their players.

Police raided the offices of FC Barcelona on Monday, carrying out several arrests just six days ahead of the club's presidential elections, a Catalan regional police spokesman told AFP.

Lionel Messi put Barcelona to within touching distance of the Champions League final on Wednesday after firing a stunning brace to down Liverpool 3-0 at the Camp Nou.

Half a year after Barcelona launched a municipal plan to welcome refugees fleeing wars in places like Syria and Iraq, Spain's second largest city is still waiting for them to arrive.

"This fills us with rage," Barcelona Mayor Ada Colau, a former activist born out of the anti-austerity Indignados protest movement, told AFP.

Barcelona have confirmed that midfielder may miss the rest of the season having ruptured a knee ligament in a nasty tackle against Roma on Wednesday.

The 22-year-old had been on the field a matter of minutes, after coming on as a second-half substitute in the 1-1 draw in Champions League Group E, when he suffered the injury in a challenge by Roma's Radja Nainggolan.

A hooded attacker opened fire Tuesday outside a hotel in downtown Barcelona near the Spanish city’s popular Las Ramblas boulevard, leaving two people injured, police said.

One person was struck by bullets while the other was hurt as they tried to flee the shooter, a regional police spokeswoman said.

Europe's aviation watchdog on Friday recommended that two people be present in the cockpit at all times, after a lone rogue pilot apparently deliberately crashed a Germanwings plane in March, killing all 150 people on board.

The European Aviation Safety Agency said all pilots should also "undergo psychological evaluation" during training or before entering service and face random drug and alcohol tests, although investigators have not cited them as factors in the Germanwings tragedy. 

Leftist activists from the Indignados (Outraged) protest movement that grew out of Spain's economic crisis took charge Saturday of city halls in Madrid and Barcelona, after thrashing the ruling conservatives in local elections.

Former judge Manuela Carmena, a communist in her youth, was sworn in as mayor of the Spanish capital early on Saturday, while 41-year-old activist Ada Colau was set to become Barcelona's first female mayor later in the afternoon.

Exit polls in Spain's local elections Sunday gave the "Indignado" protest movement a possible lead in a tight race for control of Madrid and Barcelona against governing conservative parties.

A poll by TNS Demoscopia put the protest movement slightly ahead in Madrid and Barcelona, while another by GAD3 put them slightly behind but still breaking the ruling parties' majorities.

A young teenage student was in police custody on suspicion of killing a teacher and wounding four other people at his school in Barcelona on Monday.

"A teacher is dead," killed "by a bladed weapon," just after classes started at the Joan Fuster secondary school in Barcelona, a police spokesman said.