Kolkata, Feb 13 (IANS): Brisk polling was underway in the by-election for the Bongaon Lok Sabha seat in West Bengal Friday with over 50 percent turnout seen by afternoon. The polling process is largely peaceful, an official said.

"The polling percentage was 49.92 at Bongaon till 2 p.m. The turnout exceeded the 50 percent mark after 3 p.m. The process is peaceful," an Election Commission official told IANS.

The by-poll, necessitated by the death of Trinamool MP Kapil Krishna Thakur, is being held in the shadow of the CBI inquiry into the multi-billion rupee Saradha ponzi scam.

Several Trinamool leaders, including Transport Minister Madan Mitra, are under arrest, while a number of his party colleagues have been quizzed with regard to the scandal, said to be the biggest in the state.

Adding to the significance, the deceased MP's brother Manjul Krishna Thakur quit Chief Minister Mamata Banerjee's cabinet and joined the BJP ahead of the polls.

The Trinamool has fielded Kapil Krishna's widow Mamatabala, while Manjul Krishna's son Subrata is the Bharatiya Janata Party candidate. Former state minister Debesh Das is the Communist Party of the India-Marxist nominee. Congress' Kuntal Mondal is also in fray.

A total of 15,65,447 people, including 7,55,822 women and 11 others, are eligible to cast their votes at 1,863 polling stations. The total number of candidates is 11, two of them women.

Simultaneous by-polls are being held for the Krishnaganj assembly seat where 59.93 percent voters expressed their choice till 2 p.m. The seat in Nadia district fell vacant due to the death of Trinamool lawmaker Sushil Biswas.

Among the five candidates are Trinamool's Satyajit Biswas, Apurba Biswas of the CPI-M and BJP's Manabendra Roy. The Congress ticket has gone to Nityagopal Mondal.

The strength of the electorate is 2,44,988, including 1,16,441 women and one other. There are 288 polling stations.Both Bongaon and Krishnaganj are reserved for scheduled caste candidates.