Amnesty International has called on football's global governing body FIFA to put more pressure on 2022 World Cup hosts Qatar to improve conditions for workers in the Gulf country.
Doha has made a series of reforms to its employment regulations since being selected to host next year's tournament, which has required a vast programme of construction dependent on foreign workers.
But the rights group said Qatar was at risk of slipping backwards.
"Qatar has made a number of positive reforms in recent years, partly in response to increased scrutiny after the World Cup contract was awarded," it said in a statement.
"But too often these are not properly implemented and thousands of migrant workers continue to be exploited and abused."
Amnesty said that proposals being debated by Qatar's consultative Shura Council "would undo much of the progress brought about by reforms, including by re-imposing restrictions on the rights of workers to change jobs and leave the country".
However, the proposed changes would require government approval and official sources in Doha have said they will not be accepted.
FIFA president Gianni Infantino called for fairness in assessing Qatar's rights record.
"Protection of human rights at an international level is a top priority for FIFA," he said during a media briefing Friday following a meeting of the FIFA Council.
"We need to be fair there (in Qatar) and admit a lot of progress has happened ... in the conditions of the workers. Of course more can be done everywhere, always -- even in Switzerland."
Amnesty called on Infantino to implement "independent and regular" monitoring of all 2022 sites and projects to detect and prevent rights abuses.
"FIFA has an opportunity to help leave Qatar a better place for migrant workers," it said.
On Saturday, a minimum wage of €230 a month came into force for all workers in Qatar, touted by Doha as a first for the region.
The labour ministry has said the changes will "boost investment in the local economy and drive economic growth".
In October 2019, Qatar announced plans to scrap key aspects of its controversial "kafala" labour rules, including the requirement for some workers to obtain employers' permission to change jobs and exit permits to leave the country.
Rights groups have long said the system fuelled abuses.