A total of 12,259 people accessed emergency homeless accommodation during the last week of April, the highest level ever recorded by the Department of Housing.
The overall figure includes 3,594 children across a total of 1,733 families.
Separately, the Dublin rough-sleeper count for spring was carried out over a week in early March.
It reported a reduction in rough sleeping since winter with outreach teams engaging 83 individuals, down from 91.
The total figure is an increase of 271 on March and a 22% increase on April of last year,
Charities called on Government to intensify efforts to tackle homelessness.
Focus said it showed the first impacts of the ending of the temporary moratorium on no-fault evictions.
Focus Ireland chief executive Pat Dennigan said the “most deeply worrying trend” is the further increase in the number of homeless children.
“This crisis is affecting not only the most vulnerable but individuals and families of all ages from different backgrounds.
“Their lives are put on hold as they anxiously navigate a broken housing system with supply never lower and rents that exclude those on lower incomes.
“As a nation we have failed all of those who call Ireland their home and numerous governments over the last 10 years have not listened to Focus Ireland’s advice.”
The Simon Communities said the figures represent an unprecedented number of people experiencing the trauma of homelessness.
Wayne Stanley, executive director of the Simon Communities of Ireland, said: “Sadly, we are not surprised to see the number of people in homeless emergency accommodation rise to over 12,000 this month but we have to be shocked that the situation has been allowed to get to this point.”
He said the recent announcement of projected surpluses show that Budget 2024 will be “an opportunity for the Government to reprioritise addressing the homeless and housing crisis” through the effective use of available resources.
“It’s an opportunity that cannot be missed and requires focus, planning and an all of Government response.”
Sinn Fein housing spokesperson Eoin O Broin called on Government to immediately reinstate the ban on no-fault evictions.
“This is a very significant increase in homelessness in the first month since the ending of the ban on no-fault evictions.”
He said Government did not have emergency measures in place to deal with the ending of the ban.
“The tenant-in-situ scheme is still moving too slowly.
“The output of social and affordable homes is too slow.
“No additional supply of social housing using emergency planning and procurement powers has even been initiated.
He said Government must change its approach to this “ever deepening homeless crisis before things get even worse”.
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