Polling has ended in eastern India in the first round of key state elections, as suspected Maoist rebels launched isolated attacks aimed at disrupting the voting.

Officials say rebels in the state of Chhattisgarh fired at an Indian Air Force helicopter Friday as it was leaving a polling station in Bijapur district, killing a flight engineer.

Earlier in the day, security forces said guerrillas killed one police officer and injured four others in two land mine blasts, and also snatched voting equipment and exchanged gunfire with police near polling stations.

But authorities say voting concluded peacefully at most of the more than 8,800 polling stations in the province.

Friday's polls were the beginning of a seven-week round of regional elections in six states, allowing voters to judge major parties on their handling of issues like inflation, a slowing economy and terrorism.

Four of the six elections will see a battle between India's ruling Congress Party and the main opposition Bharatiya Janata Party (BJP).

Congress and the BJP are hoping for strong showings in the state polls to help them form alliances with smaller parties ahead of national elections early next year.

Elections are being held in the states of Chhattisgarh, Madhya Pradesh, Rajasthan, Mizoram, and Jammu and Kashmir. Indian voters also will elect local governments in the capital region, Delhi.

Observers like political analyst Ajoy Bose say Indian voters are most concerned about rising food prices, the prospect of losing jobs due to a slowing economy, and a recent series of terrorist attacks in the country.

Some information for this report was provided by AFP, AP and Reuters.