Britain's electoral watchdog has fined a pro-Brexit campaign group and referred its chief executive to police for breaking spending rules during the 2016 European Union membership referendum.

The Electoral Commission says Leave.EU, which was allowed to spend 700,000 pounds ($950,000), overspent by at least 77,380 pounds and presented "incomplete and inaccurate" information about its spending.

The commission said Friday it was fining the group 70,000 pounds and referring CEO Liz Bilney to the Metropolitan Police.

Several inquiries are underway into spending and advertising during the referendum, amid allegations about the use of Facebook users' data to influence U.S. and British campaigns.

The Electoral Commission says it sees evidence that Leave.EU received donations or paid services from Cambridge Analytica, the data firm at the center of the Facebook privacy scandal.