Thousands of tenants are facing rent rises because the Government's new ban on increases will apply only to people deemed to have been financially hit by the Covid-19 pandemic.
The move has sparked fears that landlords, legally prohibited from increasing rents for the last five months, will now target tenants with significant rent rises.
Before his appointment, Housing Minister Darragh O'Brien publicly pledged to ensure the national rent freeze would remain in place until at least October.
However, legislation Mr O'Brien will bring before the Dáil this week contains only measures to stop landlords increasing rents for people who self-declare that they have lost earnings due to coronavirus.
There are around 325,000 rental households in the country and it is unclear how many will be able to avail of the ban on increases.
To prevent rent increases, tenants must be in receipt of the Pandemic Unemployment Payment, the Temporary Wage Subsidy Scheme or another form of State-funded welfare.
The Covid-specific freeze on rent and eviction ban will remain until January 10.
However, tenants whose income has fallen for any other reasons will not be able to stop rent increases under Mr O'Brien's new legislation.
Yesterday, the minister also issued what has been described as a "disturbing" threat to renters, warning that he would have them prosecuted if they try to prevent rent increases by claiming they were affected by the virus when they were not.
In an interview with 'The Business Post', the Fianna Fáil TD said: "If they're (renters) found to abuse it, we will have a certain level of audited checks on it and they will be prosecuted."
Labour housing spokesperson Rebecca Moynihan said she was very concerned about the minister's threat.
"Disturbingly, the minister plans to criminalise tenants for false declarations without doing the same to landlords availing of eviction exceptions. To do this to someone at risk of losing their home is really despicable," she said.
"The changes will only give protection from eviction until January to those who can prove they have been financially impacted by a limited set of circumstances and puts in place a complicated process to apply for that exception.
"The reality is that this will result in more people losing their home as they will have to navigate a technical system."
Sinn Féin housing spokesperson Eoin Ó Broin described the new legislation as "very worrying" and said it would lead to an increase in homelessness, which had fallen while the rent freeze and eviction ban were in place.
Mr Ó Broin said there were a disproportionate number of people who were not originally from Ireland living in rented accommodation.
He added that many of them do not speak English or have the necessary literacy skills to fill in a self-declaration form.
"The legislation is full of loopholes, the freeze will be cumbersome for those it does apply to and for many thousands of others the ordinary rules will apply which will allow landlords to issue rent increase notices," the Sinn Féin TD said.
The Government aims to rush the Residential Tenancies Bill through the Dáil and Seanad this week before the start of their six-week summer recess.