Brexit donors revealed: £32m spent on campaigning on EU referendum
Remain campaign outspent Leave by £5m
The Electoral Commission has revealed over £32million was spent on campaigning for the EU referendum campaign right across the UK.
Figures released by the watchdog showed the Brexit battle was the most expensive referendum campaign ever in British political history.
They reveal that the Remain campaign outspent Leave by a margin of more than £5m in the run up to the historic poll.
The DUP was registered as an official campaigner for the Leave side and - as revealed by the Belfast Telegraph - spent £425,622 ahead of the June 23 vote.
But investigations have been launched into the spending returns of both lead campaigns in the contest - Stronger In and Vote Leave - after the Electoral Commission watchdog found they had failed to supply all the required information about their finances.
Details of groups which spent £250,000 or more, released on Friday, showed the major Remain campaigns splashing out almost £16.2 million, compared to £11.5 million for Leave. When combined with details of smaller spenders released last November, this means the Remain campaign outspent Leave by a margin of £19,070,566 to £13,436,241.
The Leave side appears not to have spent its entire battle-chest on the campaign, with reported donations of £16.4 million outstripping Remain's combined total of £15.1 million. The two lead campaigns also received £600,000 each of taxpayers' money to help fund their campaigns.
After its initial inspection of spending returns from both sides, the Commission found that neither Stronger In nor Vote Leave had submitted all the necessary invoices and receipts to back up their accounts. The watchdog also said details of suppliers were missing for some payments.
An investigation has also been opened into missing details of suppliers, invoices and receipts in the Liberal Democrats' return, as well as into individual campaigner Peter Harris, who delivered his spending report late and without the required audit form.
The Commission is also undertaking further examination of apparent discrepancies in returns submitted by the European Movement, Ukip, Labour Leave, Grassroots Out and Conservatives In, before deciding whether to open investigations.
The Commission's director of political finance Bob Posner said: "It is disappointing that some campaigners, including both lead campaigners, appear to have not fully reported all their spending as they should have.
"Missing spending details undermines transparency and makes the returns harder for the public to understand. Where it appears campaigners have not fulfilled their legal obligations, we have begun and will continue to take action to deal with this."
A Vote Leave spokesman said: "Vote Leave's accounts were approved by external auditors and we believe we have fully complied with all the spending regulations for the EU referendum.
"Vote Leave will fully co-operate with the Electoral Commission's investigation. When we handed in our return on December 23 we realised that we had submitted it with excess spending that did not need to be reported, so it was therefore amended.
"We were also missing a handful of invoices from suppliers but these have since been provided."