The United Nations has called on Spanish authorities to launch a thorough and impartial investigation into the violence perpetrated during Catalonia�s independence referendum.

UN High Commissioner for Human Rights Zeid Ra�ad al-Hussein made the plea in a statement on Monday, voicing concern about the violence, during which hundreds were injured following clashes with police in the autonomous Spanish region.

"I am very disturbed by the violence in Catalonia on Sunday ... I urge the Spanish authorities to ensure thorough, independent and impartial investigations into all acts of violence," he said, stressing, "Police responses must at all times be proportionate and necessary."

Spanish police officers drag a man as they try to disperse voters arriving at a polling station in Barcelona, on October 1, 2017. (Photo by AFP)

The UN rights chief also urged dialogue aimed at resolving the secession issue, saying, “I firmly believe that the current situation should be resolved through political dialogue, with full respect for democratic freedoms.”

The remarks were made after Catalan authorities announced that clashes during the polling day on October 1 had left as many as 844 people injured as police tried to stop the vote from going ahead.

Catalan leader calls for intl. mediation

Separately on Monday, Catalan leader Carles Puigdemont called for international “mediation” in the crisis that has marred the independence referendum already banned by the central Spanish government.

“It is not a domestic matter,” Puigdemont told reporters at a news conference. “It’s obvious that we need mediation … which means there must be the presence of a third party, which must be international to be efficient."

He further said Europe could no longer continue to ignore the issue after almost 900 people sustained injuries, adding that Brussels lacked courage to sponsor the mediating role.

“The European commission must encourage international mediation,” Puigdemont noted. “It cannot look the other way any longer.”

Spanish civil guards drag a man outside a polling station in Sant Julia de Ramis, where Catalan leader Carles Puigdemont was supposed to vote, on October 1, 2017. (Photo by AFP)

The Catalan leader also called on Madrid to withdraw all police forces it had deployed to the region from other parts of the country.

Puigdemont said that 73 Catalans had filed official complaints against police brutality after the independence vote, calling for "detente" as Catalans reeled from the clashes.

The Catalan government says that 90 percent of voters backed the secession bid and registered a more than 42-percent turnout despite Madrid’s attempts to boycott the referendum.

EU urges dialogue in Catalonia crisis

Meanwhile, the European Union demanded dialogue for the resolution of the crisis over Catalonia�s referendum and called for an end to violence in the separatist region.

"We call on all relevant players to now move very swiftly from confrontation to dialogue. Violence can never be an instrument in politics," European Commission spokesman Margaritis Schinas said. “We trust the leadership of Prime Minister Mariano Rajoy to manage this difficult process in full respect of the Spanish constitution and of the fundamental rights of citizens enshrined therein.”

People raise their fists during a protest in Barcelona on October 2, 2017, a day after hundreds were injured in a police crackdown during Catalonia�s banned independence referendum. (Photo by AFP)

The spokesman also said, "Under the Spanish constitution, yesterday�s vote in Catalonia was not legal," but stressed that as European Commission President Jean-Claude Juncker has “reiterated repeatedly, this is an internal matter for Spain that has to be dealt with in line with the constitutional order of Spain."

Before the vote, Spain’s military police also raided the Catalan government offices on September 20, during which at least 14 junior officials and associates were arrested and almost 10 million ballot papers were seized.

Catalonia, one of Spain’s 17 autonomous regions, held a symbolic referendum back in November 2014, during which more than 80 percent of participants voted for independence, according to Catalan officials.