FORMER British prime minister Gordon Brown has called for an investigation into the finances of Nigel Farage and the Brexit Party.
Mr Brown said democracy would continue to be undermined if payments to the party were not declared.
He challenged Britain's Electoral Commission and the European Parliament to indicate whether they are investigating the party, or say whether questions over dubious payments had been answered.
Mr Brown said: "We have the potential for underhand and under-the-counter payments being made.
Leave.EU, Nigel Farage and Aaron Banks's campaign, is now under criminal investigation.
"Aaron Banks, the lead funder of Leave.EU and the friend of Nigel Farage, has been under investigation - he has made contacts with Russia. We don't know where his money comes from.
"And yet we find out last week that he has given £450,000 (€512,000) in payments to support Nigel Farage, while Nigel Farage was in a public office in the European Parliament, who should have been declaring the payments that he was receiving from anyone to avoid any conflicts of interest."
Mr Brown raised concerns over the method of payment used to process donations by supporters of the party.
He said: "Now we find the Brexit Party that has been formed is not a party, it's actually a private company. It doesn't have members, it has shareholders."
Meanwhile, Queen Elizabeth has expressed support for EU integration during a historic meeting with German diplomats, a declassified account shows.
A diplomatic cable written by ambassador Rüdiger Freiherr von Wechmar after a meeting with Elizabeth in 1988 says she left "no doubt that the future of Britain lies in Europe".
The account of the meeting, reported by German's Der Spiegel, sheds light on the private views of the monarch, who has made an effort to keep out of politics - including in the Brexit debate.
There have long been rumours that the queen privately supports European integration: she raised eyebrows at the state opening of parliament in 2017 - the first after the referendum - when she turned up wearing a blue jacket and hat with yellow flowers in a pattern resembling the EU flag.
Elizabeth is said in 1988 to have told the outgoing ambassador that "some have not realised" yet that the UK belongs in Europe - referring to her subjects.
According to the account, she is said to have noted that many British people did not yet have an understanding of the single market, and said it was "about time" for a government education campaign to explain the union to voters.