The security firm Sophos ranked countries by the amount of junk e-mails routed through computers in each nation, and found about 10 percent of all junk mail flowing around the Internet came from or passed through computers in India, the BBC reported.
India has overtaken the United States as the top spam source in less than a year, the Sophos report said, propelled by the rapid growth of the Web in the country.
The inexperience of the many first-time Internet users in India has made their computers attractive targets for high-tech criminals, Graham Cluley, senior technology consultant at Sophos, said.
"The latest stats show that, as more first-time Internet users get online in growing economies, they are not taking measures to block the malware infections that turn their PCs into spam-spewing zombies," he said.
The United States is second behind India in spam and junk mail, with South Korea third, Sophos said.