African migrants cross their hands over their heads to protest against their detention at the al-Hamra shelter in Libya's Gharian on February 2, 2018

Dozens of Sub-Saharan African migrants at a Libya detention centre got to their knees and crossed their wrists above their heads to protest their imprisonment.

They staged their protest at the Al-Hamra shelter in Gharyan, 100 kilometres (60 miles) south of Tripoli, during a visit Friday by Mabruk Mohammad al-Targui, the tourism minister of Libya's fragile unity government.

"This gesture is a call for freedom," said Saddam, from Sudan's Darfur region, who fears being forced to return to a homeland ravaged by war.

"We have been in this detention centre four months," he said. "For more than a month no organisation has come to see us."

Most of the detainees are from of Chad, Somalia, Eritrea or Darfur. Many worked and saved for years before attempting the trip to Europe, leaving behind violence and insecurity at home.

Sub-Saharan African migrants perform during an event celebrating African culture and folklore at the al-Hamra shelter in the Gharian region of Libya on February 2, 2018

But Libya itself is far from safe. Rocked by lawlessness since the NATO-backed 2011 uprising that toppled and killed longtime dictator Moamer Kadhafi, it has become a key transit country for illicit migration.

Migrants take major risks passing through the North African country.

In October, following weeks of deadly clashes around the western city of Sabratha, a major departure point for migrants attempting perilous sea voyages to Europe, more than 3,000 were arrested.

Between 800 and 1,000 were transferred to the Al-Hamra centre, where they are crammed into 12 buildings intended for around 200 people.

African migrants cross their hands over their heads to protest against their detention at the al-Hamra shelter in Libya's Gharian on February 2, 2018

On Friday the centre organised a party with African music and dance to "help them forget their suffering", according to shelter director Colonel Al-Bahloul Shananah.

He said the event also aimed to highlight "the need to intervene quickly and find solutions for these people".

But he voiced scepticism over the migrants' protest.

"They make this sign to indicate that they are detained," Shananah said. "But their presence... in the shelters is for a reason: they entered Libyan territory illegally."

"These young Africans, if we open the doors to them, they will go back to sea," he added. "We will see new tragedies and thousands of deaths."