The criticism came as local media reported on Tuesday that two Asian men had died in an "accident" while working on a construction site in the north of the country, without providing further details.
In a statement released on the eve of the fifth anniversary of the controversial decision to allow Qatar to host world sport's biggest tournament, Amnesty said the lack of substantive change "shames" the gas-rich Gulf state and FIFA, football's governing body.
2018 World Cup: Blatter claims hosts chosen before vote
"Despite massive public exposure of the appalling conditions faced by most migrant construction workers, the Qatari authorities have done almost nothing effective to end chronic labour exploitation," Amnesty said.
It urged FIFA officials and the World Cup's major sponsors to press for change.
Mustafa Qadri, Amnesty's Gulf migrant rights researcher, said: "Too little has been done to address rampant migrant labour abuse.
"The reforms proposed by the government fail to tackle the central issues that leave so many workers at the mercy of employers, yet even those changes have been delayed.
"Unless action is taken -- and soon -- then every football fan who visits Qatar in 2022 should ask themselves how they can be sure they are not benefiting from the blood, sweat and tears of migrant workers."
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Amnesty said Qatar had failed to make changes in several key areas, including giving workers the freedom to change jobs, leave the country or join unions.
"Limited progress" had been made in only two areas, wage payment and health and safety, it said.
It quoted one construction worker, named as Ramesh, who told Amnesty what happened after he complained to his boss.
"I went to my manager's office and told him I want to go home because my pay is always late. The manager screamed at me, saying, 'Keep working or you will never leave!'"
There are about 1.8 million foreign workers in Qatar, mainly from India, Sri Lanka and Nepal, with many working on major infrastructure projects directly or indirectly related to the World Cup.
That number is expected to top two million in the next few years.
There was no immediate response from the Qatari government, but Doha has unveiled labour reforms in the past few months.
In October, Qatar announced changes to its much-criticised "kafala" labour system of sponsorship -- which currently only allows workers to leave the country with the approval of their employer -- as well as regulations that allow workers to switch jobs at the end of their contracts.
It is not clear when these reforms will come into force.
Qatar also introduced a Wage Protection System in November to ensure migrant workers are paid on time.
2018 World Cup: Blatter claims hosts chosen before vote
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