At least one private sector company is believed to be on the shortlist to run a £6m Big Lottery Fund programme to help infrastructure organisations become more effective.
A senior voluntary sector figure, who did not wish to be named, said they had been given the information by a member of staff at the BLF.
The BLF announced the programme, called Assist, in December. It said the initiative would "help local support providers become more effective with help from national experts and peer-to-peer support".
Full details about how the programme will work have yet to be revealed.
The source said they were concerned about the possibility of lottery money being used to enable private companies to sell services to charities.
The source said some private companies did not have a good track record of working with voluntary organisations and that if one was chosen it also raised the possibility of the value of the fund being eroded by company VAT charges.
A BLF spokeswoman said: "We are currently in the process of procuring a lead administrator to run this initiative and are bound by EU procurement law around the information that we are and are not able to disclose.
"Therefore, we are not able to comment on which organisations have been shortlisted, but expect to select a lead administrator by spring, and will make more information about how the programme will run available at that time."