Brazil has announced a security boost of around 70,000 officers to police this year's football World Cup.In total, 170,000 people are expected to be deployed to guarantee security across the 12 host cities. The Brazil President Dilma Rousseff said the armed forces could also be brought in if needed. Since last June, protesters have staged a number of street marches, with some violent episodes, raising concerns about security at the tournament. Earlier this month, a cameraman died after being hit by fireworks apparently launched by protesters. In January, the organisers had suggested the tournament's security personnel would total 100,000 people. Around 30,000 men of the Brazilian Navy took part in military exercises yesterday.