The rights group issued a 35-page briefing saying the EU-Turkey deal to curb irregular migration was "illegal" and "reckless."
Turkey is hosting 3 million refugees, including 2.75 million Syrians, and expected to receive more as part of the deal with the EU. Under the agreement, irregular migrants who arrived to the Greek islands from Turkey after March 20 will be sent back to Turkey.
The EU, in turn, will resettle one Syrian refugee from Turkey to the bloc for each Syrian that Greece returns back to Turkey.
Turkey also stands to receive up to 6 billion euros ($6.71 billion), visa-free travel and fast track negotiations on EU accession.
The deal, according to Amnesty, is unlawful because asylum-seekers don't access "effective protection" in Turkey.
Amnesty argued that Turkey lacks the capacity to process asylum applications and falls short on key criteria to be deemed a "safe third country," AP reported.
"In its relentless efforts to prevent irregular migrants to Europe, the EU has willfully misrepresented what is actually happening on the ground in Turkey," said John Dalhuisen, Amnesty's director for Europe and Central Asia.
Turkey, it noted, doesn't accord full refugee status, and most refugees in the country don't get government support.
The organization also repeated its assertion that Syrians in Turkey are at risk of being forcibly sent back to their war-torn nation. Turkish officials have rejected prior Amnesty International reports on the issue of forced returns.