GUWAHATI, India, Oct 7 (Reuters) - People braved a steady drizzle to come out to vote in a remote northeast Indian state on Thursday, as troops guarded polling stations in an election being held under the shadow of violence.

The vote in Arunachal Pradesh, a frontier state that shares a long border with China, is the first face-off between the centrist Congress party and the Hindu nationalist Bharatiya Janata Party (BJP) since the May federal election that swept Congress to power in a surprise victory.

Although Arunachal does not have a history of violence like many other states in the volatile region, police said security was high as they did not want a recent wave of separatist attacks in the region to spill over.

More than 70 people have died in a wave of bombings and shooting by guerrillas in the neighbouring states of Nagaland and Assam since the weekend.

Analysts say Congress, which controls the 60-member state legislature, has a slight edge over the BJP, the main opposition party in Arunachal Pradesh.

Three Congress candidates have been elected unopposed, an election official said.

Election officials have travelled to remote parts of the state on helicopters and elephant back, carrying electronic voting machines. Nearly 700,000 people are eligible to vote.

The poll in Arunachal will be followed by elections in Maharashtra, India's second-largest state and home to Bombay, the country's financial hub.

New Delhi has been alarmed by the sudden burst in violence in the northeast and Home Minister Shivraj Patil said on Wednesday that more troops would be sent to the region to boost security.

Helicopters would also be deployed to help in the hunt for the rebels, many of whom are believed to be operating out of Bangladesh and Myanmar.