Development: On 8 July the federal police arrested 24 people linked to the 2005 vote-buying scandal involving President Lula da Silva's ruling Partido dos Trabalhadores.

Significance: The arrests, which snared a high-profile financier and a former mayor of São Paulo, will remind voters of the several corruption scandals that have swirled around the ruling PT since it came to power in 2002. However, the scandal is unlikely to have much impact on the government in the upcoming municipal polls on 5 October.

The so-called mensalão (monthly payments) scandal erupted in 2005 when it emerged that the PT had bought votes from legislators. The scandal forced some high-level resignations (most notably Lula's chief of staff, José Dirceu) and tainted the government, although the president's strong personal popularity rating remained remarkably unaffected by the affair.

Among those arrested was the banker Daniel Dantas, head of the Opportunity Group; Naji Nahas, an investor/financier; the former mayor of São Paulo, Celso Pitta; and Marcos Valerio, a businessman with strong links to the PT and to Dirceu (for several years the PT president) in particular. They are accused of the misuse of public funds for the purposes of congressional bribery.

The investigation has been running for four years and arrest warrants are still pending against a further 56 people.

According to local press sources, in the six years of Lula's presidency there have been more detentions for political corruption than in previous decades. In 2007 an estimated 2,800 people were detained in 188 police operations. To date in 2008, 1,700 people have been arrested in 97 operations. The government claims this is testament to increased transparency and accountability under President Lula, a claim opposition parties strongly rebuff.