Besides, there were "other issues", Aftab said without elaborating it.
Counting of votes will be held on May 23.
The opposition parties of the state claimed that the seven-phase polls reflects the "deteriorating" law and order situation under the Trinamool Congress rule, while the ruling party alleged that Centre has "misled" the Election Commission about the situation in the state.
Polls will be held for two seats on April 11, three on April 18, five on April 23, eight on April 29 seven on May 6, eight on May 12, and nine on May 19.
Aftab said while polling will be held in Coochbehar and Alipurduar in the first phase, and Jalpaiguri, Darjeeling and Raiganj in the second.
The third phase polls will witness voting in Balurghat, Malda North, Malda South, Jangipur and Murshidabad.
There will be higher number of constituencies in the next four phase polls.
The fifth phase will witness voting in Bongaon, Barrackpore, Howrah, Uluberia, Srirampore, Hooghly, Arambag.
For he sixth phase, it will be held in Tamluk, Kanthi, Ghatal, Jhargram, Medinipur, Purulia, Bankura, Bishnupur.
The seventh and last phase polls on May 19 will be held in Kolkata and two neighbouring districts. The seats are Dumdum, Jadavpur, Kolkata Dakshin, Kolkata Uttar, Barasat, Basirhat, Jaynagar, Mathurapur and Diamond Harbour.
The CEO said with the announcement of dates, model code of conduct comes into force with immediate effect.
He said an estimated 6.97 crore voters were eligible to exercise their franchise in 78,799 polling stations across the state.
To a question the CEO said the process to identify vulnerable polling stations was still on.
"We will shortly sit with all the political parties to ensure smooth and fair polls," he said.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)