The Minister of Health has been urged to appear before the Oireachtas Joint Committee on Health after representatives from the community and voluntary drugs sector warned they will be removed from the National Drugs Strategy.
Politicians also heard how there is a crisis in funding in Tallaght, where there has been a huge growth in crack cocaine use.
Anna Quigley, co-ordinator of the Citywide Drugs Crisis Campaign, warned that the Department of Health is "intending to remove our community and voluntary networks from our representative roles in the [National Drugs] Strategy" at Friday's meeting of the National Oversight Committee.
She said this will happen without any review or discussion and that it is happening at a particularly challenging time with drug use growing across communities.
Grace Hill, co-ordinator of the Tallaght Drug and Alcohol Task Force, said there is no understanding of the "colossal" issue of the impending lack of funding. She told the committee that from 1 January, there is no funding.
She said they are looking for an additional €1m, but added: "I don’t know if that’s enough for the crack issue in Tallaght".
Ms Hill said there seems to be a "block in the system" in terms of trying to get money from the HSE and the Department of Health – she said there seems to be confusion.
She said they are very worried about the service users who have been availing of their support, particularly women who have been resorting to sex work to pay for drugs and homeless people.
Sinn Féin TD Thomas Gould asked for the Minister for Health to appear before the committee "urgently" to deal with these issues.
Fine Gael Senator Sean Kyne suggested the Minister or officials in the department be "approached" ahead of Friday’s meeting.