MADRID (Reuters) – The leader of Catalonia called for international mediation on Monday to resolve a stand-off with Madrid, the day after hundreds were injured as police tried to forcibly disrupt a referendum on independence that had been ruled illegal.

“It is not a domestic matter,” Carles Puigdemont told a news conference on Monday. “It’s obvious that we need mediation.”

Sunday’s events in the autonomous region dramatically raised the temperature in a festering split between Madrid and Barcelona and made it harder for the two sides to sit down to try to find a political compromise.

Images of riot police using rubber bullets and batons in a show of force to stop the vote shocked Spain and drew international condemnation. Authorities said almost 900 people had been injured.

Puigdemont had gone ahead with the referendum in defiance of a court order. On Monday, he said the vote was valid and binding, and had to be applied.

He urged Prime Minister Mariano Rajoy to say whether he was in favor of mediation in talks over the region’s future, which he said should be overseen by the European Union.

He added that he had received no indication that the EU could sponsor this mediating role, and said Brussels had been timid and lacked courage on the matter.

In a statement issued shortly before Puigdemont made his proposal, the European Commission said: “We call on all relevant players to now move very swiftly from confrontation to dialogue. Violence can never be an instrument in politics.”

The ballot, which asked voters if they wanted an independent republic, has no legal status as it was banned by Spain’s Constitutional Court for being at odds with the 1978 constitution, which states Spain cannot be broken up.

The overwhelming “Yes” vote among the 42 percent who authorities said had made it to the polls was not a surprise as those favoring continued union had been expected to stay at home en masse. Opinion polls in the run-up to the vote had put support for independence at only around 40 percent.

On Monday, Justice Minister Rafael Catala said Spain could use its constitutional power to suspend Catalan’s existing autonomy if the regional parliament declared independence.

“We will use the entire force of the law. Our obligation is to resolve problems and we’ll do it, even though using certain measures might hurt,” he said in a television interview.