Members of the Justice and Peace Network claim the Church is starving the organisation of funds and threatening its future.
They are concerned by what is seen as preferential resourcing of Caritas Social Action Network and fear workers who retire in the next few years will not be replaced.
Chairwoman Anne Peacey said members feel undervalued. "The feeling is that they're not the priority. Voices are not being heard and justice work is a struggle at the moment."
Leading justice and peace supporter Bruce Kent raised the issue with the Bishop of Nottingham, Malcolm McMahon, at the Pax Christi AGM.
Mr Kent said that treatment of the Network was "foreign to the spirit of consultation of Vatican II".