Flyers claiming voting in the election is anti-Islamic and urging people not to vote have been branded "cowardly" by a prominent imam.
Bright yellow stickers have been posted in areas of Leicester with large Muslim communities saying voting is "shirk".
Shirk is the sin of worshipping someone other than Allah and is considered the most grievous crime for a Muslim.
Dr Ather Hussain described the signs as "laughable" and suggested it was extremists trying to cause division.
The posters have gone up in Evington and Spinney Hill, many outside mosques and Islamic charity shops.
Tim Parker, Radio Leicester Political Reporter
They are not particularly prominent as you look down the street but a flash of yellow can catch your eye as you pass the lamp-posts
I've seen in total probably around two dozen or so of these stickers, or evidence of them, with some already largely torn down.
But what is worrying is their concentration close to mosques and Islamic charity buildings.
Dr Hussain, an imam in Leicester and surrounding cities, said: "It's laughable. Logically and religiously speaking they haven't got a leg to stand on.
"I fail to see how voting would be considered as the most grievous crime possible for a Muslim to commit.
"The argument is shallow, baseless and it has absolutely no standing religiously or theologically in our religion."
And he added that those who posted the signs probably did not believe it themselves.
"If they had a sound argument perhaps they would operate in mosques and in the right public spaces.
"But quite cowardly, all they have done is put stickers all over the place without any context, without telling us who they are, without giving us any indication about where we can find more about these ridiculous beliefs."
He rubbished the argument that voting is un-Islamic, saying the Prophet Muhammad took part in the political system before and after he was revealed as a prophet.
A meeting is now planned to encourage young Muslims in the city to vote.
"Most of our Muslims appreciate and are proud of the fact that they are British and Muslim," he added.
"This propaganda is not top of our concerns."