They say in a statement:

The Electoral Commission has today announced that it has opened an investigation into allegations regarding the Conservative Party spending return at the 2015 UK Parliamentary General Election

The investigation opened by the Commission today focuses on whether the Conservative Party met their reporting obligations under the Political Parties Elections and Referendums Act (PPERA) 2000, specifically:

• whether the spending reported by the party in its 2015 UKPGE campaign spending return, in relation to the Royal Harbour Hotel Ramsgate, was notnational campaign spending and therefore should not have been included in the party’s return;
• whether spending on the Premier Inn Margate was national campaign spending and therefore should have been included in the party’s 2015 UKPGE campaign spending return.

The Commission’s sanctioning powers are limited to a civil penalty of up to £20,000…