The Institute of Fundraising is opposed to the idea of the Charity Commission charging charities for five-year 'passports to fundraise', as mooted last week.
Lindsay Boswell, chief executive of the institute, said: "While the institute is behind the need for better regulation of public collections, we would be concerned should charities face charges for acquiring certificates.
"Charges could serve to discourage charities from taking part in public collections."
But Sue Brumpton, director of the Public Fundraising Regulatory Association, said it seemed "reasonable" for the commission to charge a small fee for five-year certificates - "if it makes the process of dealing with local authorities more smooth".
She said she agreed with the decision to transfer licensing to the commission because "local authorities are not in a position to judge whether charities are fit to collect".
Provisions in the current law mean charities that carry out cash collections must obtain a permit to collect from each local authority for each campaign.
Face-to-face fundraisers collecting direct debits are not covered by the same Act - or any other - but some local authorities insist on permission being sought.