MADRID (Reuters) - Spanish authorities are preparing for protests by supporters of Catalan independence on the eve of Spain’s Nov. 10 general election that could turn violent, government and Socialist Party sources told Reuters.

FILE PHOTO: A protester waves an Estelada (Catalan separatist flag) during a demonstration outside the airport, after a verdict in a trial over a banned independence referendum,in Barcelona, Spain October 14, 2019. REUTERS/Jon Nazca/File Photo

The comments from two senior sources echoed a report in El Mundo newspaper that quoted police sources as saying plans were already in place to prevent protesters from trying to occupy polling stations.

The run-up to the vote for a new parliament has seen a series of big demonstrations in the northeastern region of Catalonia, some of which turned violent. They followed the jailing last month of nine separatist leaders over their roles in a failed independence bid in 2017.

Although the most recent protests have been peaceful, a senior source from acting Prime Minister Pedro Sanchez’s Socialist Party said police suspected some groups were planning militant actions for Nov. 9.

“They want to generate fear, confusion, a more polarized reaction ... change the meaning of the (parliamentary) vote,” the source said, without giving more details.

El Mundo said police plans to avert any violence included placing officers at the entrances of buildings used as polling stations as early as Nov. 8.

Pro-independence groups which have organized mass rallies in recent weeks say they are peaceful, and have accused Spanish authorities of presenting a false narrative of violence.

Clashes with police in Barcelona since the mid-October court ruling have often happened at the end of, or on the margins of, otherwise peaceful demonstrations.

A massive protest at Barcelona airport on Oct. 14 was a organized by Democratic Tsunami, a secretive new group which says it will challenge the ruling through peaceful means only.

It said on Twitter it was calling on followers to organize six hours of cultural, political and festive events on Nov. 9 as a way of asking the Spanish state to “reflect” on the jailing of the Catalan leaders.

“We are very worried,” a government source with direct knowledge of the situation told Reuters, referring to Democratic Tsunami’s call and the impact it could have on the election.

Opinion polls show the Nov. 10 parliamentary election, Spain’s fourth in four years, is likely to be as inconclusive as a previous ballot in April, with Catalonia’s independence drive and the protests there possibly a decisive issue.

Support for parties on the right, which traditionally take a tougher line on Catalan separatism, has increased since last month’s riots, opinion polls show, while the Socialists -- now the largest party -- could lose seats but still win.

No single party is set to secure a majority and neither the left nor right bloc is seen winning power without the help of regional parties or at least the abstention of some opponents.

Campaigning is not allowed in Spain on the eve of an election.