Brasilia: The number of Brazilians behind bars has almost doubled in a decade, rocketing the South American nation to the world’s fourth largest prison population, authorities said on Tuesday.

As of the first quarter of 2014 — the latest figures available — there were 607,700 people in prison in Brazil, according to a study by the Justice Ministry, which manages the national jail system. In 2004, there were 336,400.

Only the United States (2.2 million), China (1.6 million) and Russia (673,000) have a higher number of inmates.

The report comes as lawmakers are debating reducing from 18 to 16 the age for prosecution for serious crimes.

That would likely further burden a prison system which is already overcrowded by more than 50 per cent.