Rumours have caused panic that votes cast using the pencils provided could be rubbed out.
But council bosses have moved to reassure voters, saying the entire process is “completely and utterly secure”.
A spokesman for East Northants Council tweeted: “Following @ElectoralCommUK advice feel free to use a pen but make sure it doesn’t smudge when folding so it is clear how you have voted.
“Pencils have always been provided at polling stations for voters use.”
Another council spokesman in the north said: “The voting and electoral process is absolutely sacrosanct.
“It is fundamental to democracy and the principles of freedom of speech and the right to vote.
“The whole process is completely and utterly secure and independently validated.”