Rome, Rajab 30, 1437, May 07, 2016, SPA -- Hundreds of demonstrators clashed with Italian police on Saturday near the border with Austria as they protested at plans to tighten controls at the Brenner Pass frontier. The demonstration turned violent as about 500 protesters threw firecrackers and stones and police fired teargas in return, Italian news agency Ansa reported, according to dpa. Four police officers and several demonstrators were injured. Some 20 people were detained. The protest started on the Italian side of the border, Ansa said. Austrian police initially put the number at about 600 demonstrators, and had 300 officers on duty in case of possible riots. Austria has warned that it may reintroduce border checks at the mountain pass through the Alps along the border between Italy and Austria if migrant arrivals from Italy were to surge rapidly. On Thursday in Rome, German Chancellor Angela Merkel said in reference to tensions between Italy and Austria over the Brenner Pass: "I will do all that is possible so that problems are solved in ways other that through border closures." Italian Prime Minister Matteo Renzi said at that joint press conference that a Brenner closure would be "wrong and anachronistic." Austrian far-right presidential candidate Norbert Hofer, in a Thursday interview with Italian daily La Repubblica, compared Renzi and Merkel to traffickers of migrants across the Mediterranean, saying their alleged open-door policies were encouraging arrivals. --SPA 22:29 LOCAL TIME 19:29 GMT www.spa.gov.sa/w