Voters are being urged not to use pens when they cross their EU referendum ballot papers as it could cause them to "smudge".
Mid-way through polling day, East Northamptonshire Council tweeted out a warning, despite both ink or graphite being acceptable voting tools in the eyes of the Electoral Commission.
Concerned voters in Weymouth were told there was "not enough time for votes to be rubbed out", after Weymouth and Portland Borough Council received three calls from people wanting to clarify if they could cast their vote in pencil.
The confusion caused Manchester City Council and Hillingdon Council, west London, to tweet that pens could be used, while Sandwell Council, near Birmingham, told voters they could bring a pen but urged them not to ask staff for one.
Soon, the hashtags #usepens were circulating on Twitter encouraging pro-Leave voters to come to UK polling stations armed with pens over suspicions that their pencilled-in crosses could be tampered with.
In the UK, pencils are traditionally used for marking ballot papers and available inside polling stations for voters to use, a spokesman for the Electoral Commission said.
"However, there is nothing to stop a voter from using a pen to mark their vote - there is no legal requirement for ballot papers to be marked with a pencil," he continued.
"The reason that pencils are traditionally used is partly for historical and practical reasons: with ink pens there is always a risk that they may dry out or spill.
"Also, ink may cause some transfer of the mark the voter has made on the ballot paper when they fold it, thus potentially leading to a rejection as it may look like they have voted for more options than they are entitled to."