An election spending watchdog is to examine if election expenses run up by the Conservative party in Rochester and Strood ahead of the general election were properly declared.

The Electoral Commission has announced it is to extend the scope of its existing inquiries into election expenditure by the party.

It will consider hotel costs incurred during what is known as the ‘regulated period’ for the general election last May - a period covered by the by-election in November 2014 triggered by the defection of Conservative Mark Reckless to Ukip.

In a statement, the Commission said: “Where a Parliamentary by-election takes place during a ‘regulated period’, any campaign spending during that by-election by a political party must be reported to the Electoral Commission in the spending return they are required to submit following the election for which the regulated period applied.”

It went on: “The Rochester and Strood Parliamentary by-election... took place during the regulated period for the General Election.”

The regulated period for the general election ran from 23 May 2014 to 7 May 2015.

The commission said it would focus on two areas:

• whether hotel bills at these three Parliamentary by-electionswere campaign spending incurred by the Conservative Party
• whether the party’s campaign spending returns for both the European Parliamentary Election and the General Election were submitted in accordance with their reporting obligations set out in the Political Parties Electionsand Referendums Act 2000.

It is the latest twist in a saga that began when claims about hotel bills run up by the Conservative party at the Rochester and Strood by-election were made by Channel 4 news.

It suggested that hotel expenses incurred during the by-election were not properly reported - a claim the party has denied.

In a statement, the party said: “We will of course cooperate with the Electoral Commission. All spending has been correctly recorded in accordance with the law.”

The commission is already examining election expenses claims made by the Conservative party in the South Thanet constituency, where Ukip leader Nigel Farage lost out to Craig Mackinlay.

That commission investigation there will focus on whether the Conservative Party met their reporting obligations under the Political Parties Elections and Referendums Act (PPERA) 2000.