Jon Scourse, chief executive of the board, would not reveal the exact figure. Complaints had been received about a wide range of fundraising methods, he said, including direct mail, door drops, face-to-face and door-to-door fundraising.
"We've not had a preponderance of complaints about face-to-face, despite it being the focus of editorial coverage when we launched," Scourse told Third Sector. "Lots of people have been frustrated about all aspects of fundraising.
"Big charities have the potential to be complained about more because their fundraising activity is seen by more people."
The majority of public complaints are still at the first stage, where they are redirected to the charity concerned. Scourse said that "a small number" had reached the second and third stages of the adjudication process, but the board had yet to announce when its first set of adjudications will be published.
"It is our intention to wait until we have several adjudications before making our first findings public," he said. "Otherwise, the first charity to be found against will forever be labelled, which would be unfair."
After publication of its first adjudication report, the board plans to publish further reports after quarterly board meetings.
Separately, think tank nfpSynergy's Charity Awareness Monitor survey for March and April found that 5 per cent of people questioned were aware of the launch of the Fundraising Standards Board. Nine per cent said they had read, seen or heard about the launch of a new body to deal with complaints about fundraising.
The survey also discovered that 63 per cent of respondents were 'very' or 'extremely' concerned about charities being open, fair, honest and legal when fundraising.
The board's own analysis found that its press and PR launch campaign reached 22 per cent of UK adults, and 32 per cent of female ABC1s who give to charity.
The board now has 515 members - up by 95 since April. Scourse said more than 70 per cent were small charities with a voluntary income of less than £1m.
Got a complaint?
Stage 1: In the first instance, the Fundraising Standards Board refers complaints to the member charity
Stage 2: If the donor is not happy, the board's secretariat investigates and reaches a decision
Stage 3: If either the donor or the charity in question is dissatisfied with the secretariat's decision, the complaint is referred to the board. The board investigates and reaches a resolution.