PATNA, India -- Indian Maoist rebels killed 12 people in two separate attacks in the central state of Chhattisgarh on Saturday as they continue a campaign of violence aimed at disrupting a five-week national election.

Five election officials and two bus drivers were killed in a land mine blast while travelling from Kutru to Bijapur before planned balloting there next week, said the police director general, A.N. Upadhyay. Four people were injured and being treated in a hospital, he said.

In another attack Saturday, the rebels killed five paramilitary soldiers in an ambush on their vehicle in the remote Darbha Forest in the south of the state.

The rebels, who say they are inspired by Chinese revolutionary leader Mao Zedong, have been fighting for more than three decades for a greater share of wealth from the area's natural resources and more jobs for the poor.

Typically they target government and law enforcement officials in hit-and-run ambushes before disappearing into remote and poorly surveyed jungles within a wide swath of central India. Though they have a presence in 20 of India's 28 states, they are most active from their strongholds in Chhattisgarh, Jharkhand, Bihar, West Bengal and Andhra Pradesh.

Thousands have died on both sides in the conflict. Prime Minister Manmohan Singh has called them India's greatest internal security threat, though none of India's major political parties has said much about the rebel threat during this year's election campaign.

The multiphase election runs for five weeks and ends May 12, with results for the 543-seat lower house of Parliament announced May 16. Voting took place Saturday in the west coast resort state of Goa as well as some parts of the northeastern states of Assam, Tripura and Sikkim.

The main Hindu opposition Bharatiya Janata Party has strong momentum on promises of a surge in economic growth, and is threatening to unseat the governing Congress Party after 10 years in power.

Vowing to prevent the rebels from disrupting the vote, the government has deployed tens of thousands of police and paramilitary soldiers to guard polling booths in insurgency-wracked areas. But the rebels have only stepped up their attacks while also asking citizens to boycott the vote.