The rise in unauthorised Indians living in the US comes at a time when the number of illegal immigrants in the US fell by 7 percent to 10.8 million in 2009.
"Between 2000 and 2007, the unauthorised population grew by 3.3 million from 8.5 million to 11.8 million," said the report on Estimates of the Unauthorised Immigrant Population Residing in the United States: Jan 2009.
"The overall annual average increase in the unauthorised population during the 2000-2009 period was 250,000," the report said.
Mexico with 6.7 million (62 pc) continued to be the leading source of unauthorised immigration to the US.
The next leading source countries for unauthorized immigrants in 2009 were El Salvador (5,30,000), Guatemala (4,80,000), Honduras (3,20,000), the Philippines (2,70,000) and India (2,00,000), the report said.