In a phenomenon that is 'baffling' American border authorities, 'thousands' of immigrants from India, 'mostly young men from poor villages', entered the US illegally in 2010, crossing from Mexico into Texas, according to a media report.
More than 1,600 Indians have been caught since the influx began, mainly at the southern tip of Texas, early in 2010, the Los Angeles Times reported.
According to US border authorities, 'an undetermined number, perhaps thousands (of Indian immigrants) are believed to have sneaked through undetected', a phenomenon that is 'backing up court dockets, filling detention centres and triggering investigations'.
The migration is 'part of a mysterious and rapidly growing human-smuggling pipeline', the report said.
"The immigrants, mostly young men from poor villages, say they are fleeing religious and political persecution," the report said adding that most of the immigrants say they are from the Indian states of Punjab or Gujarat and have "common surnames" Patel and Singh.
About 650 Indians were arrested in southern Texas in the last three months of 2010 alone.
Indians are now the largest group of immigrants other than Latin Americans being caught at the Southwest border, the report said.
"The suddenness and still-undetermined cause of the Indian migration baffles many border authorities and judges," the report said.
The migration is the 'most significant' human-smuggling trend being tracked by US authorities, the report quoted deputy director of Immigration and Customs Enforcement (ICE) Kumar Kibble as saying.
"It is a dramatic increase," Kibble said. "We do want to monitor these pipelines and shut them down because it is a vulnerability. They could either knowingly or unknowingly smuggle people into the US that pose a national security threat."
In 2009, the Border Patrol arrested 99 Indians along the entire Southwest border. The journey for many of these immigrants begins from Mumbai to Dubai, then to South American countries such as Ecuador or Venezuela, according to authorities and immigration attorneys.
Guatemala has emerged as the key transit hub into Mexico.
"The roundabout journeys are necessary because Mexico requires visas for Indians," the report added.
"They sneak across the dangerous Guatemala-Mexico border and take buses or private vehicles to the closest US-Mexico border. Mexican organised crime groups are suspected of being involved either in running the operations or in charging groups tolls to pass through their territory," it said.