Police consider Newark by-election spending claims
Nottinghamshire Police is considering evidence relating to accusations of overspending by the Conservative Party during the 2014 Newark by-election.
The move follows claims by Channel 4 News that some bills were not included in local spending returns during the poll and two other by-elections.
Labour's defeated candidate in the Newark poll, which the Conservatives won, has called for an investigation.
The Conservatives say all spending was recorded in accordance with the law.
Earlier this week, Channel 4 News said it had obtained hotel bills which suggested the party broke electoral rules in the Newark, Clacton and Rochester & Strood by-elections, the first of which the Conservatives won and the other two it lost to UKIP.
Conservative MP Robert Jenrick, who won the Newark contest, told BBC News he was "very confident" his election expenses were compiled "in complete compliance with the law".
"The allegations that were on Channel 4 News are, as far as I can see, completely unfounded," he added.
Campaign spending in by-elections is limited to £100,000 for each party.
But Channel 4 News' political correspondent Michael Crick said he had uncovered £56,866.75 of undeclared hotel bills in Rochester, which would have taken the party £53,659.83 over the £100,000 limit.
The programme found bills totalling £26,786.14 in Clacton, which would have taken the party £10,835.36 over the limit, and receipts totalling £10,459.30 in Newark, which would mean an overspend of £6,650.28.
Michael Payne, who represented Labour in the Newark by-election, wrote to Nottinghamshire Police on Tuesday asking it to look into claims of "undeclared" spending by his rivals, saying he wanted reassurance that electoral laws and procedures had been complied with.
Nottinghamshire Police confirmed it had received an e-mail on the issue, adding: "This is the first communication we have received. The force will review the content of the communication, but we should make it clear that no investigation has been launched at this time."
The BBC understands that detectives in the Fraud and Financial Crimes Unit at Nottinghamshire Constabulary are handling the case.
UKIP leader Nigel Farage, whose party came second in Newark, has said the party will not make a formal complaint but he would support any complaints made by members of the public.
A Conservative spokeswoman, speaking on Wednesday, said: "All by-election spending has been correctly recorded in accordance with the law."