Private renters in England have a "toss of a coin" chance of facing eviction if they complain their home is not up to scratch, Citizens Advice has found.
This is despite measures introduced three years ago to stamp out "revenge evictions".
Citizens Advice found that private renters who formally complain about issues such as damp and mould in their home have an almost one-in-two (46%) chance of being issued with an eviction notice within six months.
It estimates this has affected about 141,000 tenants since rules were introduced in 2015 in England aiming to bring an end to retaliatory evictions, where a tenant makes a legitimate complaint to their landlord about a property but is served with an eviction notice.
A Government consultation on introducing minimum three-year tenancies in the private rented sector closes this Sunday.
Gillian Guy, chief executive of Citizens Advice, said: "The chance of a family being evicted from their home for complaining about a problem shouldn't carry the same odds as the toss of a coin.
"Those living in substandard properties must have greater protection against eviction when they complain.
"Our report shows that well-intentioned laws created to put an end to revenge evictions have not worked, and a new fix is needed.
"There are serious question marks over the existence of a power that allows landlords to unilaterally evict tenants without reason - known as section 21.
"While Government plans for minimum three-year tenancies is a step in the right direction, these changes must be strong enough to genuinely prevent revenge evictions once and for all."
Citizens Advice made the findings following a survey of over 2,000 tenants.
The research also included a survey of council environmental health officers (EHOs). It found three in every four EHOs saw tenants receive a no-fault eviction after complaining last year.
Of the officers who had been in their role before the 2015 rules came into force, 90% had not seen a drop in revenge evictions.
Citizens Advice said laws around tenant security should be "significantly strengthened".
The charity said it backs proposals for minimum three-year tenancies, but it is concerned that potential loopholes may undermine protections.
It said three-year tenancies should include limits on rent rises to prevent landlords from effectively evicting tenants through pricing them out.
A Ministry of Housing, Communities and Local Government spokesman said: "Everyone deserves a decent and secure place to live, which is why we have increased protection for people living in rented homes.
"We have introduced new measures to stop so-called retaliatory evictions but we know we need to do more and we are consulting on three-year minimum tenancies."
Chris Norris, director of policy and practice at the National Landlords Association (NLA), said: "We all want a private rented sector rid of the kind of rogue operators who would rather evict someone than make a repair.
"However, this is not an accurate picture of the situation."
He said landlords increasingly rely on "no fault" evictions as the courts are "too clogged up to cope" with repossessions claims, "and because rises in fees mean it is becoming increasingly expensive, especially as tenants may not be paying rent".
He said it "may well be the case" that the law on revenge evictions is not being properly enforced.
But he continued: "However, to force all landlords to dramatically alter their businesses in order to make up for poor enforcement, against a tiny minority of criminals, is disproportionate and would introduce significant new challenges."
Copyright (c) Press Association Ltd. 2018, All Rights Reserved. Picture (c) Yui Mok / PA Wire.