Kolkata: Polling began under heightened security in 49 constituencies spread over two districts - Howrah and North 24 Parganas - bordering Kolkata in phase four of the West Bengal assembly polls here on Monday. North 24 Parganas, a part of which falls under the world's largest mangrove forests - the Sundarbans - has 33 constituencies. The remaining 16 are in Howrah. Over 1.08 crore (1,08,16,942) voters across 12,481 polling stations, including 27 auxiliary booths, are eligible to decide the fate of 345 candidates - 40 of them female - between 7 a.m and 6 p.m. The Election Commission will use 14,353 EVMs and 680 VVPATs A total of 672 companies of central forces and 23,000 state police personnel have been deployed, in addition to other measures, to ensure free and fair polls in the two districts, considered volatile in view of their history of political clashes and poll-related disturbances in past elections. In the Sundarbans region, equipped with ham radio operations to solar lights, officials have gone the extra mile to ensure the electorate gets a chance to exercise their voting rights. In the 2011 assembly polls, the Trinamool - then an ally of the Congress - had bagged 43 of the 49 seats. The Congress had got two, the Left Front spearhead Communist Party of India-Marxist three and the Communist Party of India one. The Trinamool and the Bharatiya Janata Party are in fray in all the constituencies. The Left Front constituents and the Congress are contesting 46 seats, leaving one seat to Janata Dal-United, besides backing two independents. Khardah in North 24 Parganas district is yet again witnessing a battle between two economists - state finance, industries and information technology minister Amit Mitra of the Trinamool and Asim Dasgupta of the CPI-M. In Bidhannagar, that includes the posh Salt Lake, an abode of celebrities, top administrative and police officials, and well-heeled professionals, the Congress has nominated renowned lawyer Arunava Ghosh, who is taking on sitting legislator Sujit Bose of the Trinamool. Another constituency hogging the limelight is Kamarhati, from where Saradha scam accused Madam Mitra, now in custody, is in the race on a Trinamool ticket. Among major candidates are a number of state ministers and BJP's only sitting legislator Samik Bhattacharya. The Trinamool has given nomination to former India footballer Dipendu Biswas (Basirhat South), retired international cricketer Laxmi Ratan Shukla (Howrah North) and late Board of Control for Cricket in India president Jagmohan Dalmiya's daughter Baishali Dalmiya (Bally). Earlier, voters in 167 of the state's total 294 assembly constituencies exercised their right to franchise on April 4, 11,17 and 21 in the first three phases. Polling in the, fifth and sixth phases will be held on April 30 and May 5 for 53 and 25 constituencies, respectively.