A few arrests for fraud were reported, mostly of people with multiple voter cards.
Mr. Wilczewski said he knew nothing about the voter cards.
In many parts of the country, voter cards for 61 million registered voters were not available until Saturday.
The officials said that nearly 90 percent of an estimated 3.5 million voter cards had been distributed.
The interim government blames the international community for the delays, saying it failed to deliver voter cards and train enough poll workers.
Carry your voter card and demand that they treat your children.
By law, Nigerien electoral officials must send out voter cards two months prior to an election.
Some alleged that voter cards were denied to supporters of opposition candidates.
The drawing was used on voter cards to help the illiterate in voting.
By April 7, less than 3% of the voter cards had been distributed.