MUMBAI: A third wave of voters joined India's marathon general election, with security ramped up as the staggered polls moved to the volatile Kashmir Valley and the financial capital Mumbai.

Indian police and paramilitary forces imposed a lockdown on Kashmir's summer capital Srinagar on Wednesday to prevent anti-election demonstrations after violent protests the night before left 20 people injured.

A number of Kashmiri separatist leaders who have called for a boycott of the polls were placed under house arrest.

Nearly 145 million people are eligible to vote in phrase three of the staggered, five-stage ballot, which is widely expected to result in a shaky coalition government that will have to steer the country through an economic slump.

Polling stations opened at 7:00am (0130 GMT) with voting in most districts set to end at 5:00pm.

In Kashmir, all eyes were on the number of people casting their ballots. A strong turnout would deal a blow to separatist groups whose boycott policy is a bulwark of their opposition to Indian rule in divided Kashmir.

Two earlier rounds of voting in Hindu-dominated areas of the state passed off peacefully.

Voters were also out in India's financial and entertainment capital, Mumbai, which has witnessed an increase in "white collar" political activism since the Islamist militant attacks in November that killed 166.

Anger at India's leaders for failing to prevent the carnage has led independent candidates to stand and stirred Mumbai's traditionally apathetic educated, middle class to take part in the political process.

But national security is not considered a priority issue across the country as a whole, with the bulk of India's 714-million electorate likely to vote on purely local issues or according to their caste and religion.

"Terrorism is not uppermost in the minds of the majority of voters," said the editor of Mumbai's Loksatta newspaper, Kumar Ketkar.

Among the nine states voting on Thursday were parts of impoverished Bihar and populous Uttar Pradesh in the north, Gujarat in the west, the southern rural state of Karnataka, and leftist-dominated eastern West Bengal.

Security was tight at polling stations in Bihar and West Bengal considered at risk from Maoist rebels who marred the first round of voting two weeks ago with a series of attacks that claimed nearly 20 lives.

Smaller, regional parties are expected to play a key role in the election, after securing nearly 50 percent of the vote in 2004 and forcing the ruling Congress party into a coalition with an alphabet soup of local parties.

The month long ballot -- the world's largest democratic exercise -- wraps up on May 13, with the final results expected three days later.

With so much support going to regional parties, there is no chance of either the incumbent Congress party-led alliance or the bloc led by its main rival, the Hindu nationalist Bharatiya Janata Party (BJP) securing an absolute majority of the 543 elected seats in parliament.

Who actually ends up governing India's 1.1 billion people will be decided in what observers are calling the election's "sixth phase" -- a period of intense political horse-trading that will follow the expected fractured result.

Voting in Gujarat was given an extra touch of tension after India's Supreme Court ordered an inquiry into the role played by the state's chief minister, Narendra Modi, in anti-Muslim riots that swept the state in 2002.

A fiery orator with a lot of support among influential hardline Hindu organisations, Modi, 58, is the frontrunner to eventually succeed the BJP's current candidate for prime minister, 81-year-old L.K. Advani.

The allegation of complicity in the riots has dogged Modi for years and tainted his success in turning Gujarat into an economic powerhouse.