Dozens of migrants and refugees aboard a merchant vessel at a Libyan port are refusing to disembark for fear of "detention and torture", rights watchdog Amnesty International said on Friday.
It said in a report that the group of at least 79 refugees and migrants, including several children, have been aboard the boat in the western Libyan port of Misrata for a week.
The UN's refugee agency UNHCR said the boat had arrived in Misrata on November 10 with 95 refugees and migrants from Ethiopia, Eritrea, South Sudan, Pakistan, Bangladesh and Somalia.
Since then, 14 have left the vessel.
The others, Amnesty said, should not be "forced to disembark to be taken to a Libyan detention centre where they could face torture and other abuse".
Their boat was intercepted in the Mediterranean on its way to Europe and was brought to Libya by a Panamanian flagged merchant vessel "in clear breach of international law", Amnesty said.
It urged Libyan, European and Panamanian authorities to ensure the safety of those on board.
"Libya cannot be considered a safe place to disembark," Amnesty said.
"The protest on board the ship now docked in Misrata gives a clear indication of the horrifying conditions refugees and migrants face in Libya's detention centres where they are routinely exposed to torture, rape, beatings, extortion and other abuse," said Heba Morayef, Middle East and North Africa director for Amnesty International.
"Under international law, no one should be sent to a place where their life is at risk."
There was no immediate comment from Libyan authorities.
Amnesty urged Libyan authorities "to expedite the opening of a long-awaited processing centre that will house up to 1,000 refugees and asylum seekers allowing them to relocate out of detention centres".
Plunged into chaos following the fall and killing of longtime dictator Moamer Kadhafi in a 2011 NATO-backed uprising, Libya has become a prime transit point for sub-Saharan African migrants making dangerous clandestine bids to reach Europe.
People smugglers have taken advantage of the turmoil, putting African migrants seeking to reach Europe at greater risk.
Many migrants, intercepted or rescued at sea, find themselves detained in detention centres where they face dire conditions.
UNHCR estimated that some 679,000 registered migrants were living in Libya as of June 2018, though the actual number could be closer to a million.
The situation in Libya's detention centres "continues to deterioriate" because of food shortages and the spread of diseases including tuberculosis, UNHCR warned Wednesday.