"The Commission has issued directions that in future integrated violet sketch pen of specific design and manufactured by a particular firm -- both approved by ECI -- shall be used in all future elections," the EC said.
"Such pen will be the instrument for recording preferences on ballot paper by the voter and at the time of poll, it shall be given to each voter by the designated polling officer and shall be taken back from him after the voter comes out of the voting compartment," it added.
The top poll panel said that any deviation from it will "not be allowed under any circumstances".
The commission said that it has clearly defined the role and responsibilities of Chief Electoral Officers in the above mentioned elections.
In Haryana, 13 of the Congress votes in the 90-member assembly were deemed invalid because they were marked with a different pen than provided by the EC.
This invalidation of votes gave an unexpected victory to BJP-backed media baron Subhash Chandra over Congress-backed candidate RK Anand.