An MEP has complained after a series of election boards advertising his party went missing.
Derek Clark, UKIP MEP for the East Midlands, says signs went missing in Roade and Towcester.
Eleven of the boards, which read “Vote UKIP”, disappeared on Sunday and Monday.
But a spokesman for Northamptonshire County Council said although council workers had not removed the signs, putting election boards up on public highways was a form of flyposting.
The spokesman added: “It is an offence to fix signs to structures on the highway under the Road Traffic Act 1980 and we will take action to remove them where we are made aware of them.”
UKIP sources had accused other parties of stealing the signs.