Tickets for next year's World Cup in Brazil will be "cheapest ever", football's governing body Fifa says. Fifa Secretary-General Jerome Valcke said 70% of the matches would cost less than in previous events; ticket prices will be announced on 19 July.Mr Valcke and Fifa President Sepp Blatter praised the Confederations Cup in Brazil which ended on Sunday.The tournament was marked by protests against the high cost of the World Cup, corruption and poor public services.Mr Blatter said the Confederations Cup was a success despite the demonstrations which took millions to the streets."I am happy we come to a conclusion now with a sporting result and the impression that the social unrest is now resting - I don't know how long for," he told reporters in Rio de Janeiro on Monday.'Some uncertainty'The head of Fifa also admitted there had been fears that Brazil would not be ready for the World Cup in 2014.Building work at some stadiums was finished shortly before the start of the Confederations Cup and there were doubts about how the country's infra-structure would cope with a large scale event."When we started the competition there was some uncertainty what would happen," Mr Blatter said.Fifa officials avoided commenting on security issues, saying they were a matter for the government to deal with.During the Confederations Cup there have been several clashes between protesters and security forces, who fired rubber bullets, pepper spray and tear gas into the crowds.