The Conservative Party has been fined a record £70,000 for irregularities in their election expenses - including money it spent fighting South Thanet at the general election of 2015.

An investigation conducted by the Electoral Commission concluded that there were significant failures by the party to report accurately how much it spent campaigning at three by-elections in 2014 and at the 2015 UK Parliamentary general election.

The Conservative Party’s 2015 UK Parliamentary general election spending return was missing payments worth at least £104,765.

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The investigation was triggered by claims that expenses that should have been attributed to local costs were wrongly recorded as national expenditure or not reported at all.

The party’s spending on its election battle bus - used to bring party activists to help fight key marginal seats including South Thanet - was one focus of the inquiry as was spending totalling £18,000 at hotels where activists and campaign organisers stayed.

The commission also found that payments of £118,000 were either not reported at all or wrongly reported.

The Electoral Commission said there was a "realistic prospect" the money had given the party an advantage.

The Met Police has been asked to investigate some aspects of the commission’s findings.

North Thanet MP Sir Roger Gale queried the timing of the announcement saying it could compromise ongoing police investigations related to similar election expenses allegations.

Kent Police is conducting a separate inquiry into related claims about spending in South Thanet by the Conservatives.

It has yet to complete that investigation, which focuses on whether expenditure at hotels should have been recorded as local expenditure rather than national spending.

The Conservatives said the party had accepted last March they had made "an administrative error" and said it would pay the fine.

The Prime Minister says the party would pay the fine. In an interview, Theresa May said the party had “complied fully with the Electoral Commission” even though the watchdog said the Conservatives had been unreasonable and uncooperative during the inquiry.