The Electoral Commission said its investigation of the party’s fundraising methods is “ongoing”, after visiting its headquarters amid the growing controversy.
After the visit, the Brexit Party claimed the Commission had found “no evidence of any electoral offences”.
But, in a statement, the watchdog said seeking small sums via online donations “open up additional risk in relation to compliance with UK political finance law”.
“This risk is that it increases the potential for individuals or organisations to evade the permissibility rules, which primarily seek to prevent significant sums entering UK politics from overseas.”
The Commission stressed that it was the Brexit Party’s “responsibility” to “ensure it has the systems in place to maintain its compliance with the law”.
“Our review of the systems in operation by the Brexit Party is ongoing,” it added.
“This will inform our regulatory work following the European Parliamentary elections and any recommendations we make to the party.”