Project Scotland claims the details of the “Hogmanay Ambassadors” initiative should have been clear before a lucrative new deal was signed off by the city council.
Chief executive Paul Reddish said the omission raised questions about the event’s commitment to the volunteers who come forward.
Underbelly, the firm awarded an £800,0000 contract to produce the event in March, have come under fire from politicians, union leaders and campaigners against exploitation in the hospitality industry for their recruitment drive.
It was launched at the end of last month to try to find two 150-strong teams of unpaid managers, supervisors and ambassadors to work on 30 December and Hogmanay.
However, they will only get meal vouchers and “reasonable” travel expenses for working at an event worth around £40 million to the city.
Underbelly claimed it was the victim of a “sorry climate of bashing success” and accused critics of belittling the motivations of volunteers and confusing “real issues around getting people into paid and secure employment”.
Writing in The Scotsman, directors Charlie Wood and Ed Bartlam said: “Of course businesses should be held to account and act responsibly, but there are those in other positions of responsibility who should think twice before jumping on assumptions to wrongfully undermine the success of flagship occasions to the detriment of all.”
Mr Reddish said: “I don’t think that it is unreasonable to question Underbelly’s approach to offering volunteering opportunities to ensure they are genuinely that.
“Those of us involved in volunteering professionally work to a number of ethical boundaries which we believe should not be crossed.
“For example, it is simply not appropriate in any scenario to use volunteers to replace paid jobs, or to take part in roles core to the delivery of a particular service previously run by employees. Volunteering opportunities also need to be designed with the benefits to the volunteer at the forefront.
“I would expect that, as part of any bid to win the Hogmanay contract, that volunteering should have been explicitly mentioned given the scale of the programme, and safeguards put in place to protect and cover these points.”