Another worker, from India, described receiving threats from his employer after complaining about not being paid.
"He just shouted abuse at me and said that if I complained again I'd never leave the country," Nabeel, whose name was changed to protect his identity, said.
"Ever since I have been careful not to complain about my salary or anything else. Of course, if I could I would change jobs or leave Qatar."
Amnesty called on football's world governing body, FIFA, to put pressure on Qatar to publish a "comprehensive reform plan" ahead of construction peaking in the middle of next year.
On Thursday, FIFA released a statement in response to the report, saying it was "fully aware of the risks facing construction workers in Qatar and of the opportunity that FIFA, together with other stakeholders, has to facilitate the improvement of working conditions in the country."
While acknowledging challenges remained, FIFA said it was confident "the structures and processes set-up so far by the Supreme Committee for Delivery and Legacy (SC), which is the entity responsible for the delivery of FIFA World Cup infrastructure, provide a good basis to monitor labor rights of migrant workers on FIFA World Cup stadium construction sites."
For its part, Qatar's SC said it was "committed to ensuring the health, safety and well-being of every worker on FIFA World Cup projects."
The SC said it had maintained a constructive working relationship with labour organisations, including Amnesty International, and that the conditions reported "were not representative of the entire work force on Khalifa."
"We have always maintained this FIFA World Cup will act as a catalyst for change – it will not be built on the back of exploited workers," the SC went on to add. "We wholly reject any notion that Qatar is unfit to host the FIFA World Cup."