Tens of thousands of supporters  protested Monday in Barcelona as Catalonia’s former leader Artur Mas went on trial for holding a non-binding independence referendum in 2014 — a move he defended as legitimate.

The trial has stoked pro-independence fervour in Spain’s wealthy, northeastern Catalonia region at a time of high tensions between the local separatist government and Madrid.

Shouting “independence, independence”, and “we want to vote,” some 40,000 people gathered on a wide palm tree-lined avenue next to the courthouse, many of them holding separatist red, yellow and blue flags in strong gusts of wind.

Mas, Catalan president from 2010 to 2016, and two former members of his government are accused of serious civil disobedience and misconduct for having organised a symbolic, non-binding referendum in November 2014 despite a ban by Spain’s Constitutional Court, which deemed it illegal.

“I am responsible for everything,” Mas told the court, speaking in Catalan even when the judge addressed him in Spanish.

“My initiative and that of the government had deep, clear and purely democratic roots.”