Names on Michael Lowe's nomination form for the East Retford South ward on Bassetlaw District Council included three Labour supporters and a former Labour councillor, MP John Mann said.
Nottinghamshire Police said the matter had been referred "for consideration".
The local UKIP party said it would not comment as police inquires continued.
Mr Mann, who is running for re-election as the Labour MP in Bassetlaw on 7 May, tweeted earlier a police investigation was underway into the allegations.
Kevin Sly, whose name appears on the nomination form alongside those of his two daughters, Gemma and Jessica Sly, said they had been interviewed by officers.
"I'm not very happy at all," said Mr Sly, who describes his family as Labour supporters but not "active" members of the party. "I don't even know the guy."
Mr Sly, who lives in Ordsall, Nottinghamshire, near Retford, said the signatures alongside their names were not real.
Mr Mann said another person whose name was on the form, Anne Moore, was a Labour supporter who lived in the same town.
Signatures of 10 registered electors from the ward in which the candidate is standing must be obtained in order to apply, the Electoral Commission states.
David Scott, UKIP candidate for Bassetlaw in the general election, said Mr Lowe, who unsuccessfully contested the Worksop West seat at the county council elections in 2013, would not comment while a police investigation was under way.
Also standing in the Retford East seat in the district elections:
Standing in the Bassetlaw seat at the general election:
Police are looking into claims a UKIP council candidate in Nottinghamshire "forged" signatures on his nominations form.