The by-poll will be held on September 30 along with the elections to two seats in Murshidabad district - Samserganj and Jangipur - where polling was countermanded during the eight-phase assembly elections conducted earlier this year due to death of candidates.
The EC has also appointed two senior IAS officers G Prakash and S Chockalingam as general observers for Samserganj and Jangipur respectively, the official said.
Prakash and Chockalingam were IAS officers of 2000 and 1996 batches of Tamil Nadu and Maharashtra cadres respectively.
Votes will be counted in the three seats on October 3. PTI SCH