The opposition alleged vote rigging and intimidation by activists of the ruling Trinamool Congress in West Bengal, where polling was unsually high even by national standards.
Officials said over 60 percent of the 88 lakh electorate had voted within six hours.
The battle for Lok Sabha 2014 has become vocally bitter, with the Bharatiya Janata Party (BJP), which is determined to unseat the Congress, and others locked in a no-holds-barred campaign.
Even as polling continued in Bihar's seven seats, BJP's prime ministerial aspirant Narendra Modi told an election rally in Valmikinagar that the Congress was on the run.
Dwelling on an emotive issue, Modi denounced the Congress-led UPA government for not hitting back after Pakistani troops beheaded Indian soldiers along the Jammu and Kashmir border.
Wednesday is the penultimate round of the 10-leg parliamentary election that began April 7 and will end May 12. The millions of votes cast across India will be counted May 16.
