For years Libya has been a stepping stone for Africans seeking a better life in Europe. Syrian refugees fleeing the conflict at home are also making their way to Libya to try to reach the West.
"The ghastly conditions for migrants, coupled with spiralling lawlessness and armed conflicts raging within the country, make clear just how dangerous life in Libya is today," said Amnesty's Philip Luther.
The situation has worsened since the NATO-backed 2011 uprising that toppled veteran dictator Moamer Kadhafi, with powerful militias battling for Libya's oil wealth and two governments vying for power.
Feeding on the chaos, people smugglers have stepped up their lucrative trade. The flow of migrants also rises when sea conditions improve in warmer months.
"With no legal avenues to escape and seek safety they are forced to place their lives in the hands of smugglers who callously extort, abuse and attack them," Luther said.
Amnesty's Middle East and North Africa director urged the European Union to deploy more rescue vessels in the Mediterranean while tackling smugglers at the same time.
"Introducing measures to tackle smugglers without providing safe alternative routes out for the people desperate to flee conflict in Libya, will not resolve the plight of migrants and refugees," he said.
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The rights group also called on Tunisia and Egypt to ease border restrictions with Libya, in order to provide migrants -- who would otherwise embark on a dangerous sea journey to Europe -- haven.
The Amnesty report, "Libya is full of cruelty", details testimonies of abuse, sexual violence, exploitation or religious prosecution.
Charles, a Christian from Nigeria, told Amnesty he was beaten and abducted by armed gangs in Libya several times.
Others have spoken of abuse at the hands of smugglers, who they say treat them like "animals".
Women migrants complained of sexual abuse, with one saying she was "gang-raped" by 11 men after her husband was tied to a pole and forced to watch.
Amnesty quoted Syrian refugees as saying smugglers moved them to boats in poorly ventilated refrigerator trucks.
It also criticised Libya's policy of locking up illegal migrants in detention centres where conditions are dire.
Libyan officials, who have complained of a lack of means, have said that 7,000 illegal migrants are being held in 16 detention centres across the country awaiting deportation.