Many private landlords in Wales will now need to give six months' notice before evicting tenants, under a change to the law due to the pandemic.
The Welsh Government said the temporary law meant fewer people would face homelessness.
But a Senedd committee warned the way the change was made risked breaching landlords' human rights.
The government said it was content that the law was compatible with the European Convention on Human Rights.
The law, which affects assured shorthold tenancies and assured tenancies, will last until 30 September, although this could be extended.
At the start of the pandemic, under the Coronavirus Act, the law was changed so landlords would have to give tenants three months' notice for eviction, instead of two.
Housing minister Julie James has now extended that by a further three months - with the except of evictions which relate to anti-social behaviour.
"The purpose of these temporary alterations is to ensure landlords give increased notice to tenants facing eviction from rented properties before landlords can issue proceedings for possession," she wrote, in a government statement.
"The effect will to be to further delay evictions during the ongoing public health emergency; fewer people will face eviction into homelessness at a time when local authorities are less able to respond to these situations."
She added that those renting their homes would benefit from "increased security and reduced anxiety", while people at risk of eviction would be provided with "increased time to seek support to resolve any problems".
Citizens Advice Cymru had called for the three-month period to be extended to six in July.
It said calls for help with rent doubled during lockdown, with 1,037 between 24 March and 23 June this year, compared to 497 during the same period last year.
The Welsh Government is planning on making a similar law permanent via new legislation, tabled in the Senedd before the pandemic began and yet to be passed.
The National Residential Landlords Association said the news was a "real hammer blow".
Chief executive Ben Beadle said: "Even after this, it is unlikely the courts will be able to hear these cases straight away, so landlords could quite easily be looking at 18 months with no income."
But housing charity Shelter, which has called for an end to no-fault evictions, said the change was welcome.
Director John Puzey said: "This will give any tenants who are in arrears some breathing space to seek financial advice and try to negotiate an affordable repayment plan with their landlord."
Plaid Cymru's Delyth Jewell called for the Welsh Government to go further and ban no-fault evictions.
"Whilst an extension on protecting tenants from evictions is welcome, the Welsh Government's move simply doesn't offer long-term reassurances for tenants," she said.
Landlords given 'only a matter of hours' notice
The Senedd Legislative, Justice and Constitution committee said the way the law was made ran "the real risk" of breaching landlords' human rights to property.
Under the European Convention on Human Rights, people are "entitled to the peaceful enjoyment" of their possessions.
The committee raised concerns that the law had been made without the Welsh Government explaining why interfering with this right in such a way was justified.
The law had been imposed, in common with many other changes related to the pandemic, by a minister without a vote in the Senedd.
A letter from the Welsh Government to the committee said that, due to the urgent nature of the law, there had been no time to carry out a consultation.
But the committee said landlords were given "only a matter of hours'" notice - the law was made on 23 July and came into force the next day.
The lack of a consultation or a impact assessment "undermines" any justification the law was proportionate, a report from the committee said.
What has the Welsh Government said?
A Welsh Government spokeswoman said: "Given the urgent need to ensure the number of tenants under threat of imminent eviction is kept as low as possible, these regulations were brought into force the day after they were made to prevent landlords issuing an eviction notice before the regulations came into effect.
"All landlords affected were informed of the existence of the regulations immediately through Rent Smart Wales.
"We are content that the provisions are compatible with the European Convention on Human Rights and we are continuing to examine how we can support the private rented sector to cope with the impact of the virus."