Calcutta, India - Mihir Kumar Basu hires construction workers for a low-cost housing project on Calcutta's east side. To find cheap labor, Mr. Basu travels about 60 miles northeast of the city to the villages and towns along India's border with Bangladesh. There, illegal Bangladeshi immigrants line up for the chance to make a few dollars a day at his site.
"A lot of the people who work here have come to India illegally, many of them within the past few years," Basu says. "They don't have proper documentation to be in this country, so they're very scared to talk about it."
That's because the Indian government is trying hard to find and deport them. India says 15 million to 20 million Bangladeshis have slipped across the porous 2,500-mile border over the past several decades, settling in border towns as well as in major cities like Calcutta (also known as Kolkata), Delhi, and Bombay (Mumbai).
The government says the migrants, most of whom are Muslims, pose an increasing security threat to the country. Indian intelligence authorities allege that some of these people are acting as agents for Bangladesh-based Pakistani spies and possibly even Al Qaeda terrorists. India has increased its spending on border security by 36 percent to $41 million.
But underlying India's much-trumpeted concerns about national security, many experts say, is a more subtle fear of the demographic changes that are reshaping the country's eastern front, creating majority-Muslim enclaves along the border. Now Indian politicians across the political spectrum are trying to capitalize on increasing anti-Muslim sentiment.
A government report published last December showed dramatic population increases in border areas throughout eastern states like Assam and West Bengal over the past 10 years. In some towns, the population increase was more than 20 percent, almost entirely from poor Muslim immigrants, according to the report.
"In some areas you can't find a Hindu family because the population mix has been so disturbed," says Tarun Ganguly, a former editor of a leading Calcutta newspaper whose research organization, the Center for Social Research, studies West Bengal's ethnic demographics. "There is a fear here among Hindus that they are being swamped by the Muslims."
While top politicians from the Hindu nationalist Bharitya Janata Party (BJP) are spearheading the campaign to weed out illegal immigrants, the effort is winning support from states and political parties that normally oppose the BJP.
That is partly because antiterrorism and border control initiatives are always popular, but also because Hindu nationalism has gained momentum in many parts of India over the past several months - all parties are eager to court Hindu voters. After Hindu-Muslim riots ravaged the western state of Gujarat a year ago, the BJP played the religious card in December's statewide elections and won an overwhelming victory. That victory may have encouraged the BJP and other political parties to cater to Hindu voters, who make up more than 80 percent of India's population.
In West Bengal, a communist-led government that has traditionally defended the interests of the minority Muslim community is now supporting the move to oust illegal Bangladeshis. The Indian border security forces said Sunday that some 462 Bangladeshis have been held in detention near the Indian border in the past two months. And the state government has started cracking down on informal Islamic schools, or madrassahs, that have sprouted up along the border.
Many people here find it hard to believe that destitute agricultural laborers and low-wage service workers could have ties to terrorists.
"These are starving people trying to make a meager living," says Reena Bhadhuri, an expert on Islam at Calcutta University in West Bengal. "How can they be connected to Al Qaeda and the Pakistani intelligence agencies?"
But Indian officials say this kind of poverty can create the ideal conditions for terrorists to infiltrate the country. India is particularly worried that the terrorists will lend support to ethnic separatists who are waging insurgencies in India's northeastern states. A host of militant groups in seven different states have demands ranging from increased autonomy to outright independence from India.
Many ordinary Muslims in Calcutta support tighter border security but say the policy of removing those who have already settled shows how anxious India is to get rid of Muslims.
"Sending these people back is not the correct thing to do, because these people are settled here and have been working here for years," says 22-year-old Akhtar Hussein, who runs a general store in central Calcutta.
Mohammed Sajjad Alam, a newspaper vendor, notes that while the Indian government says it is afraid of terrorism, the real menace it sees is the growing Muslim population. "They worry that if too many Muslims come here and settle, they might form a majority in some areas and seek more political representation," Mr. Alam says.
If deporting Muslims is sensitive, deciding what to do with Hindu illegal immigrants, estimated by some experts at 1 million to 2 million, could be even more vexing for India. Many of them say they came here to escape increasing Islamic fundamentalism in Bangladesh.
Kalipado Das left Bangladesh with his wife and two daughters in 1987, fleeing what he says was torture at the hands of his Muslim neighbors. Mr. Das now lays bricks at Basu's Calcutta construction site. "I wouldn't go back, even if they paid me double to work there," Das says.
Indian officials say Hindu refugees might deserve special treatment. "If they have come here illegally, it may be justified because of the hostility they face in Bangladesh," says I.D. Swami, deputy minister for national security. "Some distinction will have to be kept in mind."
Identifying illegal immigrants, particularly in urban areas, will be a great challenge for the state police officials who will be charged with carrying out the deportation drive. Bangladeshis speak and look like Indian Muslims in West Bengal. And many Bangladeshis have been able to get legal residency documents like ration cards and voter identification cards from local political-party officials looking to shore up their vote banks.
India is planning to issue new electronic identity cards in several states to better track Indian citizenship.