THE Liberal Democrats' former Northern Ireland spokesman has called for the DUP to reveal the exact source of its £435,000 Brexit fund.
Alistair Carmichael also raised concerns about rules governing political donations, suggesting they may need to be tightened.
Sir Jeffrey Donaldson, who was the DUP's Brexit campaign manager, told The Irish News yesterday that the money from the shadowy Constitutional Research Council (CRC) "complied fully" with Electoral Commission requirements.
He insisted the funds had been raised "legitimately" but refused to say whether the party had asked CRC chairman Richard Cook where it came from.
"We are satisfied that the Constitutional Research Council is a bona fide organisation and that has been confirmed with the acceptance of the donation and the requirements," Sir Jeffrey said.
"We are satisfied that the money has been raised in a legitimate way and the Electoral Commission has accepted our return."
With Sinn Féin last night saying the DUP had questions to answer about the donation, Sir Jeffrey accused The Irish News of failing to scrutinise Sinn Féin and its donors to the same degree.
The money given to the DUP - almost five times as much as it spent on last year's assembly election campaign - was used partly to buy advertising space for the Leave campaign in the Metro newspaper, which is not circulated in Northern Ireland.
The identities of party benefactors are withheld in the north under legislation dating from the Troubles, but the DUP succumbed to growing pressure in February when it revealed the donation came from CRC.
An investigation by website openDemocracy has found that Mr Cook, a former Scottish Conservative parliamentary candidate, previously founded a wealth management company with a former head of the Saudi Arabian intelligence service.
It also revealed his associations with Dane Peter Haestrup, who has repeatedly been linked to a gun running case described by Indian authorities as “the biggest crime in the country's history".
Mr Haestrup has never been charged with any crimes linked to the case.
Mr Carmichael, outgoing MP for Orkney and Shetland, said he was not satisfied with the DUP's response.
"It is obviously important for the integrity of the democratic process that the source of the funding should be known as well as legitimate – not just the person registering the donation but how and where they got their money," he said.
"I personally have no reason to doubt the role of the DUP but if others have questioned it, it's appropriate that they are able to demonstrate due diligence – that's what would be expected in the rest of the UK."
Mr Carmichael said the episode had highlighted potential flaws in the legislation governing political donations.
"I think there are a number of people in Westminster who look at the chain of financing and who now wonder if parliament may need to revisit the way it in which works," he said.
