A Hamilton city councillor who sent a photo of a hacked road sign containing a sexual joke to a female journalist has apologised.

Mark Bunting sent the photo of the two electronic signs to journalist Angela Cuming which read "Jesus is cuming" and "open your mouth".

Cuming posted the photo to Twitter, describing it as a "grossly inappropriate and offensive 'joke'".
Mr Bunting apologised for sending it.

"You might see a thread on Twitter about a meme I sent privately to someone whom I thought was a mate," he said in social media posts.

"I misjudged the humour and offended them as a result. Needless to say I feel terrible about it and regret what was an error of judgement and I apologise unreservedly."