BARCELONA, Spain (AP) — Three people were arrested late on Monday in a protest against negotiations between Spain’s acting government and Catalan separatist parties over a possible amnesty for thousands involved in Catalonia’s independence movement.

Government authorities said that the arrests took place during a gathering by over 3,000 people in front of the national headquarters of Spain’s Socialist Party in Madrid. Two men were arrested for violent behavior against police, and one woman for disobedience, the representative of Spain’s national government in the Madrid region said.

The leader of the far-right Vox party, which holds the third-most seats in the national Parliament, was at the rally. Several protestors waved Spanish flags and pushed back against police in riot gear. There were other similar protests in other Spanish cities, but no additional arrests were reported.

Spain’s acting Prime Minister Pedro Sánchez, the Socialists’ leader, blasted the protests, saying they were being led by “reactionaries.”

“(I extend) all my warmth and support for the Socialist Party members who are suffering harassment by reactionaries at their local headquarters,” Sánchez wrote on X, the social media platform formerly known as Twitter.

“To attack the headquarters of Spain’s Socialist Party is to attack democracy.”

Sánchez is negotiating with the Catalan separatist parties to receive their backing in his bid to form a new government and keep his center-left coalition in power following an inconclusive national election in July. But the two separatist parties have demanded a sweeping amnesty that would include their leaders who fled Spain following their failed 2017 secession attempt, in exchange for their votes in Parliament, among other concessions.

That has angered many in Spain, including leading opposition parties on the right who accuse Sánchez of bending to lawbreakers.

Spain’s conservative Popular Party, the main opposition party, has called for its own protest against the amnesty negotiations for Sunday, in public squares in each provincial capital.

“I am not going to allow that my country has to ask forgiveness to those who attacked its institutions,” Popular Party leader Alberto Núñez Feijóo said.

There had been other protests in recent weeks, but they had remained peaceful.

Sánchez has until Nov. 27 to form a new government or the Parliament will be automatically dissolved and new elections called for January.

Despite losing steam in recent years, Catalonia’s separatist movement retains strong support in the wealthy northeast region including control of the regional government.