A founder of the Gay and Lesbian Equality Network, GLEN, has hit out at the decision to wind down the group.
Arthur Leahy has called for a meeting of all key stakeholders to "ascertain whether there is a viable alternative plan".
The decision to close the charity came after it appointed former Senator Jillian van Turnhout to carry out a comprehensive review of the organisation.
The review was brought about by concerns over the use of funds for non-GLEN political campaigns, and the use of company credit cards for private purposes.
The charity's board said it would transfer key services to other agencies as soon as possible.
Statement by the board of GLEN
Read the full statement here: https://t.co/Kxpnq4IH9O pic.twitter.com/Z1YGHh0LIk— GLEN (@glenLGBT) May 18, 2017
In a statement, Mr Leahy said: "I want to express my disagreement and sadness at the closure of an organisation with an enormous record in driving the changes in the LGBTI community over the last 30 years.
"I have just read the independent report of ex-Senator Jillian van Turnout on the organisation and fail to agree with her recommended closure.
"She has outlined a number of minor governance issues and stresses that there was no question of missing finances as was suggested in earlier coverage. Why such drastic action?
"The consultative process of the report was very inadequate, very few key stakeholders were consulted given the implications of the decision.
"As someone who had been involved from the outset I was not consulted at any stage, this would indicate the limits of the process."
"A wrong decision"
Mr Leahy added: "It is particularly sad given the commitment of the many GLEN workers headed by Brian Sheehan who over the years contributed far and above what was required and as a result produced such significant results.
"At any visits to the offices those levels of courage and dynamism were clearly apparent."
Mr Leahy also said he believes the "forced resignation" of former chairman Kieran Rose was "a crucial mistake".
Mr Rose resigned in April, saying he regretted that financial arrangements made between him and GLEN were contributing to controversy.
On this issue, Mr Leahy said: "Kieran was the driving force in terms of vision, energy and commitment and without his presence the organisation was extremely vulnerable.
"Due process should have awaited the Independent report before such a damaging decision was taken. It is now proven to be a wrong decision.
"I would propose that the decision to close should be suspended and call for meeting of all key stakeholders to ascertain whether there is a viable alternative plan and to consider what is in the best interests of the wider LGBTI community," he added.