"The final percentage of voting will be higher and known later as queues were reported in many booths beyond the end of polling at 5 pm," state's Chief Electoral Officer Debasish Sen said.

Altogether 45 companies of central paramilitary forces and 75 companies of state police personnel were deployed.

Rajganj in Jalpaiguri district registered 75 per cent votes, the highest, and Alipore in Kolkata the lowest of 45 per cent, Sen said.

According to him, 12 people were arrested from West Midnapore and North 24-Parganas districts for electoral malpractices and on charges of impersonation.

The byelections are considered to be a dress rehearsal for the 2011 state Assembly elections, with the contest confined to the CPI(M)-led Left Front and the Trinamool Congress-Congress combine.