Kidnappings in Argentina have increased more than fivefold in the last two years, official figures show.
Argentines took to the streets last month to protest at rising crime
According to Buenos Aires' ministry for security, there were 46 reported cases in the country in 2001 and 306 in 2003, Clarin newspaper reported.
In cases reported last year, kidnappers netted 3.32m pesos ($1.15m).
Correspondents say the country has long prided itself on the safety of its streets, but has experienced a surge in violent crime.
In 2002 Argentina defaulted on almost $88bn of debt, in the midst of its worst-ever economic crisis.
The primary motive to get involved in kidnapping is because it "makes more money, more quickly", investigators said.
In May, thousands of people took to the streets of Buenos Aires to demand government action after a wave of kidnappings and brutal murders.
The protest was convened by the parents of 23-year old Axel Blumberg, who was kidnapped and murdered in April.
Argentina's President Nestor Kirchner has said that many of the kidnappings carried out in and around Buenos Aires were masterminded by corrupt police officers, several of whom have been arrested.