The Conservative party is facing further questions about its election expenses during the acrimonious campaign for South Thanet last May.

The claims have been made by Channel 4 news which said that it had seen bills for hotels that had not been included in returns submitted by the party to the Electoral Commission.

The new claims focus on the hotel costs for campaign workers who were sent to the constituency in the hard-fought campaign with Ukip.

Channel 4 said the £4,000 bill for accommodation for six campaign workers who stayed at the Premier Inn in Margate were not included in official returns.

The broadcaster also said that the costs of newspaper wrap-around adverts for the Conservatives published by the Thanet Extra - part of the KM Group - had been categorised as national party expenditure, meaning they did not have to be included in the constituency returns.

Had the hotel expenses and adverts been added to the expenses, the total would have been more than the limit permitted for constituency campaigns, according to Channel 4.

The party has insisted that its expenses were reported correctly and in line with the rules but were questioned by the Ukip leader Nigel Farage.

He told Channel 4 he did not intend to make a formal complaint himself and neither would Ukip but others might. "I would be very surprised if a member of the public didn't make a complaint. I have no doubt that what happened in Thanet was in breach of election law."

He defended his own party's expenses, saying they were compliant with the rules.

The Electoral Commission, which oversees elections, has confirmed that it is to consider the Conservative party's submissions for South Thanet.

In a statement, it said:

“The Electoral Commission has begun an assessment regarding items of expenditure included in the Conservative Party’s 2015 UK Parliamentary General Election national campaign spending return."

"This includes items of expenditure relating to the Royal Harbour Hotel in Ramsgate. Specifically, in relation to rules under the Political Parties, Elections and Referendums Act (PPERA) 2000, whether the return contained payments that were not party campaign expenditure."

The statement added:

“Once the Commission has concluded our assessment,either decide that no further action is necessary or begin an investigation. If appropriate, we may also refer the matter to the police."

“The rules around candidate spending and any potential criminal offence are matters for the police to investigate under the Representation of the People Act (RPA) 1983. The police are able to assess any complaints they may receive under the RPA independent of any assessment the Commission is making of potential offences under PPERA.”