Argentina is using drones to catch tax evaders who fail to declare mansions and swimming pools.
Unmanned aircraft sent over a rich area of Buenos Aires discovered 200 homes and 100 pools that had not been detailed on returns.
Tax officials said the drones took pictures of luxury houses standing on plots registered as empty. The evasions found by the drones amounted to missing tax payments of more than US$2 million ($2.5 million) and owners of the properties have been warned they face large fines.
The unregistered mansions and pools were found in an area about 15km south of the city and, according to the tax agency, they appeared to be large and constructed with "premium materials".
Countries in South America have expanded the use of drones, deploying them for purposes as diverse as locating drug smuggling routes, monitoring crops and looking for archaeological sites.
According to the Council on Hemispheric Affairs, most of the drone technology being sold to South American governments and companies - US$500 million worth between 2005 and 2012 - comes from Israel, but drones are also being produced cheaply in Mexico.
The proliferation has raised concerns among human rights activists. Speaking to Upside Down World, a magazine of South American politics, last year, Alejandro Sanchez, senior research fellow at the Council on Hemispheric Affairs, said: "Anyone thinking drones are financially unattainable for less developed countries hasn't looked at the latest models.
"There's definitely a need for a technology that's both cheap and can have some really positive results."