Residents' lives could be put at risk, a mayor has said, after the government refused a council's plans to continue its private landlord licensing scheme.
Liverpool City Council wanted to extend the scheme to crack down on rogue landlords for another five years.
Mayor Joe Anderson said the "ill-thought out" decision puts "some of our most vulnerable tenants at risk".
But the government said "robust evidence" needed to support the application was not met.
A spokesman said Liverpool had recently received funding to tackle rogue landlords.
Under Liverpool City Council's scheme, which launched in 2015, private landlords are required to hold a licence before they can rent out accommodation.
Government approval is needed for schemes which cover more than 20% of a council area.
Communities Secretary Robert Jenrick has turned down Liverpool's application for a five-year extension from April.
Mr Anderson, who said the scheme had been a "great success", said the council was considering a legal challenge.
The council said the decision would "severely hamper attempts to drive up standards in the private rental sector" and keep private tenants safe, particularly in relation to fire safety.
In order to be granted a licence, landlords have to carry out safety checks on their properties and register their details with the council.
Liverpool City Council said it had carried out more than 37,000 compliance actions and prosecuted nearly 250 landlords since the scheme began.
It said 70% of inspected properties in the city had been found to be in breach of their licence conditions.
Serious hazards such as fire, electrical safety and excess cold were uncovered.
Without the scheme, the council would not have the same powers to gain access to properties, it said.
A spokesman for the Ministry of Housing, Communities and Local Government said: "Liverpool City Council was one of more than 130 local councils to recently receive a share of £4.3m funding from government to tackle rogue landlords.
"We will continue to support Liverpool City Council and other local authorities in taking effective enforcement action as part of our commitment to securing a better deal for tenants across the country."