Bill McKinnon, who has helped to co-ordinate a series of grassroots pro-independence marches, claims a newly incorporated firm has wrested control of donations given to the All Under One Banner group.
However, other organisers accused Mr McKinnon of trying to personally profit from the movement, and said that the group was overhauling fundraising procedures in order to guarantee its financial security.
The prominent All Under One Banner movement boasts more than 30,000 followers on Facebook, and has attracted tens of thousands of people to its rallies.
Mr McKinnon, a director of AUOB Limited, said he had handled money from online crowdfunding appeals and paid expenses for marches, with all his accounts audited.
But he said that he has had “no access” to funds raised via bucket collections at three recent marches.
He claimed the newly formed AUOB Scotland – which has two directors, Mandeep Singh, and Shaun Moore – has “taken control” of the collection funds.
Mr McKinnon said: “This dispute has been ongoing since June, so it covers marches in Dundee, Bannockburn, and Inverness.
“An enormous amount of cash could be potentially raised in Edinburgh [a march is planned for October] and I don’t know where that’s going.
“The new group want us to hand over all the money in the AUOB account, but we refused to do that and said we would talk about it after Edinburgh and at the end of the financial year.
“That was when they started their own company and took over the buckets.”
The most recent march organised by All Under One Banner was through Dundee.
SNP MP Stewart Hosie, who represents Dundee East, was one of those on the march. He estimated that 16,000 people took part.
AUOB has said it will organise regular marches “until Scotland is Free”. Previous AUOB events this year have taken place in Dumfries, Bannockburn and Inverness.
The Edinburgh march is planned for Saturday, 6 October, and the full procession route is expected to be: Princes Street Gardens, Princes Street, The Mound, Mound Place, Ramsay Lane, The Royal Mile, South Bridge, Cowgate, Holyrood Road, Holyrood Gait, Queens Drive, House Wynd, Grounds of the Scottish Parliament.