The controversial issue of illegal immigration from Bangladesh has for long haunted Assam, and the subject is picking up steam once again with assembly polls due early next year.

Since the past month, the state has been witnessing a campaign to oust Bangladeshi migrant workers with an unidentified group distributing leaflets asking them to leave or else face action.

The group has also stuffed leaflets through letterboxes and sent messages on mobile phones telling people not to employ "illegal foreigners". Many of these Bengali workers were engaged in brick kilns and pedal rickshaws in Assam, besides doing menial jobs.

Joining the bandwagon of protests against illegal aliens is the influential All Assam Students' Union (AASU), besides political parties of all hues, particularly the Bharatiya Janata Party (BJP). 

"The presence of illegal Bangladeshis is a threat to India's national security and could also overwhelm the indigenous population in Assam and other parts if not checked," senior BJP leader Pramod Mahajan warned in a recent meeting of party workers in Assam. 

The BJP even accuses the ruling Congress government in Assam of encouraging Bangladeshi migrants for vote bank politics.

For the AASU, the issue dates back to the early 1980s when Assam was in the grip of a massive anti-foreigner uprising that later saw some of its leaders forming the Asom Gana Parishad (AGP), a regional political party that rode to power in 1985 on the anti-Bangladeshi plank.

But once in politics, the AGP could do very little to solve the problem, with nearly 80 percent of the 272-km long border that Assam shares with Bangladesh remaining unfenced. 

"The AGP was in power in Assam and its ally, the BJP, was at the centre. If the AGP and the BJP were so concerned about Bangladeshi infiltration why did they not fence the border during their rule?" asks Chief Minister Tarun Gogoi. 

"At least we are sincere in our effort. We are expediting the process of fencing the border to check any infiltration."

Analysts say the Bangladeshi immigration issue invariably gathers momentum ahead of polls in Assam - an emotive issue that political parties try to cash in on.

"Why do the BJP and other parties try to whip up this issue only when elections are around the corner?" asks Hafiz Rashid Choudhury, leader of the United Minorities Front (UMF), a political party in Assam. 

"Does infiltration take place only when elections are due in Assam?"

However, the AGP is maintaining a moderate stand this time in what is seen as an attempt to woo voters of the Muslim minority in Assam who account for about 30 percent of the state's 26 million people.

"Indigenous people should not be harassed in the name of evicting foreigners," said a senior AGP leader.

Muslim voters are a decisive factor in at least 40 of the 126 assembly seats.

"The Congress party is silent on the foreigners issue as it depends on Bangladeshi voters whose names are enrolled in the electoral rolls," another BJP leader said.

The infiltration issue will further gain ground, but once the polls are over the controversy may as usual die down.