The Conservative Party's failure to accurately report its 2015 General Election expenses means there is a "realistic prospect" that candidates gained a "financial advantage" over opponents, the elections watchdog has said.
The Electoral Commission fined the Tories a record £70,000 for "numerous failures" in reporting its expenses for the 2015 General Election, and three by-elections in 2014, and referred the party's former treasurer to the police.
Cumbria Police is one of 12 forces to have submitted files to the Crown Prosecution Service, in relation to the Conservatives' spending.
The Conservatives accepted the fine but their claim that they complied fully with the investigation was questioned by the Commission, which revealed it had to go to court to obtain certain information from the party and criticised its "unreasonable uncooperative conduct".
It comes with the Tories under pressure on numerous fronts, including a dramatic U-turn on Budget tax rises, the Scottish Government's demands for a second independence referendum, and as Theresa May prepares to trigger Brexit by the end of the month.
And it follows the news that a dozen police forces, including Cumbria Police have sent files to the Crown Prosecution Service as part of a parallel probe in to the Conservatives' 2015 election expenses.
A Conservative Party spokesman said there needs to be a review of how the Electoral Commission's processes could be improved:
Political parties of all colours have made reporting mistakes from time to time.