Brazilian government bonds are suffering the biggest quarterly losses since the run-up to former President Luiz Inacio Lula da Silva's election in 2002 led to speculation that the nation would default.

Dollar-denominated bonds from Brazil, Latin America's biggest nation, plunged 7.55 percent since the end of March, the biggest slide since a 16 percent drop in the third quarter of 2002 before Lula's October election that year. The loss this quarter exceeds a decline of 6.15 percent for countries with triple-B ratings, according to Bank of America Corp.

Investors are becoming concerned that President Dilma Rousseff's administration is undoing the progress of her mentor and predecessor, who overcame bondholder skepticism to win the nation's first-ever investment grade in 2008. Brazil is now grappling with inflation above its 6.5 percent target, the prospect of a credit downgrade and the biggest street protests in more than two decades as speculation increases that the Federal Reserve will reduce its unprecedented bond buying, which had pushed investors into higher-yielding emerging markets.