Recounting their ordeal, some of the returnees said the slave trade is a joint venture between Libyans and some Nigerians.
They described the Nigerians involved in the slave business as more wicked than the Libyans and other participants.
A recent CNN reports revealed the auctions of Africans, including Nigerians, in Libya.
The shocking report has since generated global outcry and condemnation.
President Muhammadu Buhari had ordered the evacuation of Nigerians stranded in Libya following the scandal.
Recounting their ordeal, some of the returnees said they also sold by Nigerians.
"Nigerians and Libyans are doing the business like they are one big happy family," Harrison Okotie, 32, who lived in Libya for three years until his repatriation, told Punch.
Another returnee, Sunday Anyaegbunam, who hails from Edo state, said they were sold twice by Nigerians during their nine-day journey through the desert.
According to Anyaegbunam, he left Nigeria along with his wife in April 2017.
He said their Nigerian "burger" (trafficker) sold them to a set of Libyan traffickers at Agadez, Niger, where they were subsequently sold to another Nigerian who took them to Sabha, Libya.
They were separated into different cells when they got to Sabha.
He recalled, "We were made to contact our families on the phone and I had to ensure the payment of N400,000 for my release and N300,000 for my wife.
"The Nigerians selling people in Libya are more wicked than many of the Arabs. I have never seen people so heartless as the Nigerians who bought and sold me.
"There are many of them in Agadez and Sabha, who are making so much money from selling their own people. But there are other West Africans doing the business too.
"When you approach them and say, 'please, my brother, help me', they would tell you, 'no brother in the jungle.”
Esosa Osas, another Nigerian who was in Libya for six months, said she also confirmed that Nigerians were selling other Nigerians in Libya.
"You dare not talk to them, else they would beat you and lock you up.
"I noticed that the connection houses were also controlled by Nigerian women," she said.
Kelvin Sunday, 21, who was in Libya for seven months, also recounted how they survived in the desert by drinking their own urine.
Sunday said he gathered N965,000 to get to Libya with the help of family and friends.
"We were in the desert for three days without food or water...we were drinking our urine to survive. It got to a point that when there was no more urine to drink, we started to drink fuel," he said.
The Libyan government has ordered an investigation into the alleged slave trade.