Campaigner Fr Peter McVerry says the Department of Social Protection is creating homelessness by not increasing rent allowance rates.
His stance follows today's Sunday Times report which shows the number of homeless people has actually increased since an action plan was announced by the Environment Minister Alan Kelly last December.
A homelessness summit, as well as a €25m plan was announced by Minister Kelly, following public outcry over the death of homeless man Jonathan Corrie outside Leinster House.
But Fr McVerry, says government departments need better co-ordination on the issue.
He said: "They are going in different directions. While the Department of the Environment has special responsibility for homelessness, and is doing what it can to create solutions to homelessness, the Department of Social Protection, who give the rent supplement, are actually creating homelessness.
"By refusing to increase the rent supplement, hundreds and hundreds of families have become homeless over the last 18 months."