Human Rights Watch warned Tuesday that Syria's new property law does not satisfy international standards and amounts to the "forced eviction" of vulnerable people unable to prove land ownership.
The controversial law, known as Decree 10, allows Syria's government to seize private property for zoned developments, compensating owners with shares.
The owners inevitably lose their property and can only claim shares if they prove ownership within 30 days after the zone is announced.
On Tuesday, HRW said the law violates standards meant to protect owners from forced evictions set forth in the International Covenant on Economic, Social, and Cultural Rights (ICESCR).
Decree 10 affects "property rights without due process or compensation, amounting to forced eviction and property seizure for owners whose property rights are not recognised," the rights group said.
The ICESCR stipulates that any property law provide for real consultation with those affected, adequate notice before the eviction date, and sound legal remedies.
"The law's 30-day period, as well as a right to appeal under Law 10 that does not halt the eviction until the appeal is decided, does not comply with these requirements," said HRW.
"The apparent lack of access and capacity for refugees affiliated with anti-government groups to lay their claims means that there is no opportunity for genuine consultation," it added.
Syria's brutal war has forced more than five million people to flee the country and displaced another six million internally.
It is these displaced families who will be most at risk of losing property, rights groups have warned, as many do not have the right paperwork, or legal and financial resources to make a claim.
As a result, HRW said, Decree 10 is "a significant obstacle to return".
"Law 10 is a worrisome addition to the Syrian government's arsenal of 'urban planning laws' that it has used to confiscate property without due process or compensation," said HRW's deputy Middle East director Lama Fakih.
"Countries and donors supporting reconstruction in Syria have a responsibility to consider the obstacles this law poses to returning for millions of displaced Syrians," she said.