Meanwhile, exit polls conducted after the first three phases of the elections show a clear lead for the Bharatiya Janata Party (BJP) and its allies, with the Congress party coming in second.

Most of the violence took place in Bihar where several landmine explosions killed security forces and poll personnel deployed during the vote.

The BBC's Satish Jacob in Varanasi: "BJP is suffering from the anti-incumbency factor"

Seven people were also killed in violence in the troubled state of Kashmir. Three of them died when security forces opened fire to break up an anti-election demonstration.

India's election commissioner, M S Gill, has deplored the violence and has urged political leaders to address the issue.

Violence in Bihar

Bihar's top police official, K A Jacob, told the BBC that at least 30 people - 21 of them policemen - were killed in a series of landmine attacks across the state.

Five policemen died in Hazaribagh, southern Bihar, when their jeep was blown up by a landmine while they were on a patrol.

BBC Correspondent Daniel Lak's eyewitness account of the voting from Jehanabad

Other attacks on paramilitary forces took place in Palamau, Chatra and Sasaram. Armed men were also said to have looted ballot boxes.

Bihar is notorious for election violence, which often involves attempts by workers of rival parties and private militias to seize polling booths.

The latest attacks were blamed on left-wing extremist groups who had called for a poll boycott.

The violence occurred despite extra security forces deployed in anticipation of trouble. Some 47,000 paramilitary forces and policemen were guarding more than 29,000 polling stations.

The state - part of the northern Hindi heartland - is witnessing a straight contest between the BJP and the Congress, both of whom have forged alliances with rival regional parties.

The BBC's Daniel Lak, who was in the central Bihar district of Jehanabad, said there were some instances of voter intimidation and electoral fraud.

Large numbers of women turned out to vote

In the southern state of Andhra Pradesh, a Congress party activist was reported to have been killed.

But polling was brisk and peaceful in the states of Uttar Pradesh and Madhya Pradesh, where voting also took place.

In Madhya Pradesh, monsoon flooding meant that voters had to take to tractors, boats and mules to reach polling stations.

BJP gains

The turn-out on Saturday's voting was estimated at 53%, lower than on the first two phases.

South Asia Correspondent Mike Wooldridge: "The authorities had been braced for potential trouble"

Despite the scale of violence in Bihar, 57% of the state's voters cast their ballot.

Meanwhile, exit polls on state television show a clear lead for the BJP in the first three rounds of voting.

The BJP and its allies are projected to win 191 of the 344 seats in which voting has been completed. The Congress and its allies were set to win 129.

Kashmir clashes

In Kashmir, protesters claimed that soldiers were trying to force them to vote in the constituency of Baramulla.

The BBC Srinagar correspondent said polling was low with hardly any voters showing up at some polling booths.

Separatists have called for an election boycott in the state and disrupted voting in the first two rounds.

More than 90 million people across five states were eligible to vote in the third stage of polling.

Two of the states - Uttar Pradesh and Bihar - account for nearly a quarter of seats in parliament.

Voting is staggered in five phases over a month to avoid spreading security forces too thinly in traditional trouble spots.

The last two phases will be on 25 September and 3 October. Counting of votes starts on 6 October.