(CNN) A small blue boat with an outboard motor bobs on the waves of the open sea. It is crammed with 28 migrants -- men, women and children -- from Somalia, Bangladesh and Yemen. Across the horizon is the Libyan coast.

The sailors prepare to throw a rope to the boat, but several men on board shout back, in Arabic: "We don't want it."

"You don't want it?" asks one of the sailors. "You'll die out here!"

After several attempts, the sailors manage to throw the rope on to the boat's bow. A passenger throws it with an air of disdain into the water.

The sailors toss the rope again, and again the migrants throw it in the water.

They've paid hundreds of dollars -- a huge fortune -- for this leg of their perilous journey to the shores of southern Europe. It has cost them several thousand dollars to get to this point from their home countries. This is not how their odyssey was supposed to end.

No love between rescuer and rescued

Since the beginning of 2014, 18,990 people have died trying to cross the Mediterranean, according to the International Organization for Migration (IOM).

Even slightly rough seas can sink small, crowded boats like this. No one aboard has a life vest.

Eventually a Libyan sailor dives into the sea, swims to the boat and attaches the rope. His comrades pull the boat alongside.

Reluctantly the migrants climb on board the Libyan Coast Guard ship. "This is worse than death," laments a woman.

Mona, 17, left Somalia after her father died. She said she was tortured by traffickers.

The sailors herd the migrants onto deck. Twenty-two of them are Somalian, five are Bangladeshi, and one is from Yemen. There is no love here between rescuer and rescued.

Abdel Samad, from Somalia, spent six years in Libya, saving up the money to pay traffickers to get to Europe.

"The Libyans thrash us," he says. A Libyan sailor overhears Abdel Samad.

"You're all cursing Libya, you animals!" he bellows in Arabic, adding in English, "Shut up!"

For him, patrolling the seas and stopping migrant boats is a job for which sympathy isn't a requirement.

"I live near [Tripoli's] international airport. It's a war zone. But I didn't run away like the migrants do," he said.

Libya is a key transit point along the central Mediterranean route. Many who get stuck there are intercepted and detained by the Libyan Coast Guard, which is funded and trained by the European Union. The Coast Guard is under the control of the UN-recognized Government of National Accord (GNA), based in Tripoli. The EU has paid the GNA and its Coast Guard more than $250 million to stop migrants and refugees from crossing the Mediterranean.

Workers from the International Organization for Migration receive the migrants when the coast guard ship arrives in Tripoli later that night.

From there, they're taken to a variety of GNA-run detention centers around Tripoli, including the Tariq al-Sikka center.

Libyan migrant detention centers have come under criticism by human rights organizations. The centers receive indirect funding from the EU.

Detainees remain in centers indefinitely

There are more than 655,000 migrants originating from more than three dozen countries in Libya, according to data collected by the IOM between June and July 2019. Almost 6,000 of them are held in detention centers.

The centers are intended to hold -- against their will -- those caught trying to cross the Mediterranean. According to several humanitarian organizations, many detainees remain in these centers indefinitely. Women and children are not recognized as requiring special attention and remain vulnerable to abuse and ill-treatment, according to the Global Detention Project, a non-profit human rights organization based in Geneva.

Human rights organizations, such as Human Rights Watch, have criticized conditions at the detention centers and blame EU policies for contributing "to the abuse of migrants in Libya." But the EU, driven by differences between member states, has not changed its policy regarding migrants in Libya despite its glaring shortcomings. Italy and the European Union continue to broker deals with Libyan forces to control migration, according to the Global Detention Project.

"European Union (EU) migration cooperation with Libya is contributing to a cycle of extreme abuse," HRW wrote in a January 2019 report . "The EU is providing support to the Libyan Coast Guard to enable it to intercept migrants and asylum seekers at sea after which they take them back to Libya to arbitrary detention, where they face inhuman and degrading conditions and the risk of torture, sexual violence, extortion, and forced labor."

Laki traveled from Somalia to war-torn Yemen and then went through Sudan before finally arriving in Libya.

The EU did not immediately respond to CNN's request for comment. The EU has argued that it needs to protect its borders from illegal migration.

The Libyan government has declined to comment about the conditions and the abuses in detention centers reported by NGOS.

UN urges release of migrants

Of the eight women interviewed in the section of the Tariq al-Sikka center designated for women and children, seven alleged they were raped, some repeatedly, on their journey to Libya. All declined to give their last names. None of the women said they had been raped while inside the detention center.

The UN has repeatedly urged Libyan authorities to release detained migrants, and said they had "serious concerns" about their safety and conditions amid the ongoing conflict in the country.

"Migrants should be released from detention centres as a matter of urgency, and should have access to the same humanitarian protection as all civilians, including access to collective shelters or other safe places," UN High Commissioner for Human Rights Michelle Bachelet said in a statement this April

"No one helped us," said 18-year-old Danayt from Eritrea, her voice quavering as she recalled her treatment at the hands of her traffickers. "They beat us with belts. They raped us. Then they fed us. Then they raped us."

Danayt is pregnant, and terrified at the prospect of giving birth in a detention center with little in the way of medical care. She broke down in tears and covered her face.

Abdel Naser al-Ahzam, an official with the GNA's Interior Ministry, is the director of the Tariq Al-Sikka detention center. He slams the claims that detained migrants aren't receiving medical treatment as "lies."

"Everyone gets treated as needed. Their claims are lies," said al-Ahzam.

Laki, from Somalia, cradled her baby, wrapped in a pink blanket. She was sitting on a bare mattress in a hot, crowded room.

She traveled from Somalia to Yemen -- another country ravaged by war -- then through Sudan before finally arriving in Libya.

Danayt, an 18-year-old migrant from Eritrea, said traffickers beat her group with belts, and repeatedly raped them.

Along the way, traffickers demanded more money, but she didn't have any.

"I was tortured, forced to work, and raped. Then I became pregnant and gave birth to this baby," she said.

She alleged she was last raped in June 2018 in Kufra, a town in southeast Libya, and then again in Bani Walid, south of Tripoli.

"I saw the hell with my eyes," she said. Her message to relatives back home? Despite your hunger and your problems, don't come to Libya."

Rocking her baby, she said she bore no ill will towards the life she clutched in her arms.

"Praise God who blessed me with this baby. I can't throw it away. The baby is part of my body," she said.

Laki, 18, did however have a simple plea: "Take me from here."

Mona, 17, also came from Somalia. She left home, she recalled, because her father died and her mother had no means to support her and her siblings.

In Kufra, the traffickers, who she believes were Libyans and Chadians, demanded that Mona or her family pay them more money. She couldn't come up with the cash.

"So they beat me. They tortured me. And one night, three men cornered me, took me outside and raped me," she said, her eyes filling with tears. "At that moment, I hated myself. I wanted to die.

"These are people who want a better life," al-Ahzam said. "They're escaping wars and misery. They're not criminals."

He believes that inmates are receiving sufficient care at the center. "They tell us these stories. We sympathize with them. But it's all according to their stories. The support [we give] is for anyone. Raped or not," said al-Ahzam.

Perhaps overwhelmed with the task of caring for more than 700 people in his center, al-Ahzam doesn't have much time for the horror stories the migrants tell. For many of the inmates here, the future is grim, as they live their lives in limbo at the mercy of Libyan authorities, and their backers in the EU.