Hindu nationalist Narendra Modi, the prime ministerial candidate for India's main opposition Bharatiya Janata Party (BJP), takes a "selfie" with a mobile phone after casting his vote at a polling station during the seventh phase of the general election in Ahmedabad April 30, 2014. REUTERS/Amit Dave

By Sujoy Dhar, Frank, Jack and Daniel

KOLKATA/NARAYANGURI (Reuters) - Hindu nationalist Narendra Modi, the prime ministerial front-runner in India's mammoth general election, on Sunday reiterated his strong stance against illegal immigrants, just days after a wave of sectarian killings in the north-eastern state of Assam.

India is in the home stretch of a five-week election, which has heightened ethnic and religious tensions in many parts of the country and in which Modi's opposition Bharatiya Janata Party (BJP) looks set to emerge as the biggest group.

India deployed troops in Assam on Saturday after more than 30 Muslims were gunned down in three days of what police said were attacks by Bodo tribal militants, who resent the presence of settlers they claim are illegal immigrants from Bangladesh.

Modi has repeatedly called for tighter border controls and last week said illegal immigrants from Bangladesh living in the state of West Bengal should have their "bags packed" in case he came to power.

At a rally on Sunday he accused the West Bengal state government of being soft on illegal immigrants because it was looking to secure votes from ethnic and religious minorities.

"You are concerned about infiltrators and not your own people ... they must go back, they are robbing the youths of India of their livelihood," Modi told the rally in the state, which borders Assam.

Police on Sunday said the death toll from the Assam attacks now stood at 34 after they found the bodies of two 30-year-old women floating in the Beki river near Narayanguri village, where the worst of the attacks took place.

A man's body was found elsewhere in the same district. All of the victims were Muslims.

Fifteen people have been arrested in connection with the attacks, including 10 forest guards employed by the state government and five former militants, police said.

Bodo tribesmen have long argued many of the Muslims in their part of Assam state are illegal immigrants encroaching on ancestral lands.

In 2012, clashes erupted in which dozens of people were killed and 400,000 fled their homes. Assam also has a history of armed groups fighting for greater autonomy or secession from India.

On Saturday, Prime Minister Manmohan Singh of the ruling Congress party condemned the latest attacks in Assam. Law Minister Kapil Sibal accused Modi of making divisive comments.

"This violence has a long history," BJP spokesperson MJ Akbar said on Sunday. "This knee-jerk reaction of blaming Narendra Modi for everything is absurd."

Bangladesh's Information Ministry did not immediately respond to a request for comment on Modi's latest speech.

LOCAL RIVALRIES

Assam state police said the latest outbreak of violence seems to have been sparked by the longstanding local rivalries, with Bodo tribesmen attacking Muslim settlers as punishment for not supporting their parliamentary candidate in the election.

Residents of Narayanguri village, where the worst of the attacks took place, said eighteen bodies were wrapped in black plastic sheeting and buried on Sunday.

Soldiers and paramilitary police continued to guard the village in the wake of the attack.

"They opened fire with no warning," said Shalam Gaon, the 40-year-old village head, who was cycling home from a nearby market town on Friday when he heard gunfire and saw flames.

Voting in India's election, the world's largest ever democratic exercise, concludes on May 12 and results are due on May 16.

Several opinion polls have forecast the BJP will emerge with the biggest share of the 543 parliamentary seats up for grabs, although the party could fall short of a majority.

Critics have long accused the BJP of deep-seated prejudice against India's Muslims, who make up more than 12 percent of the country's 1.2 billion population. The BJP says it only opposes preferential treatment for any community.

(Additional reporting by Ruma Paul in DHAKA; Writing by Shyamantha Asokan; Editing by Sophie Hares)