After escaping, with hundreds of others, from an overcrowded Libyan detention centre where guards shot dead six migrants, Sudanese refugee Halima Mokhtar Bshara says she just wants to leave the country.

"They attacked us, humiliated us, many of us were wounded," said the 27-year-old from Sudan's war-torn Darfur region.

"We're at the end of our tether."

The Al-Mabani facility in the capital Tripoli was at triple its capacity following police raids against migrants last week, when guards shot six people dead on Friday.

Libyan authorities round up migrants who attempted to join a mass breakout from an overcrowded Tripoli detention centre after guards shot dead six inmates
Libyan authorities round up migrants who attempted to join a mass breakout from an overcrowded Tripoli detention centre after guards shot dead six inmates AFP / Hussam AHMED

The shooting was "related to overcrowding and the terrible, very tense situation," the International Organization for Migration (IOM) said.

Some 2,000 migrants and refugees escaped in the chaos, including Bshara and her three children.

On Saturday, the Libyan interior ministry denied any "excessive use of force" against escaping migrants.

It said that as "hundreds" of people being held at the detention centre escaped, "a stampede" occurred during which "an illegal migrant died and others were wounded, including several police officers".

Libya is a favoured departure point for migrants from sub-Saharan Africa risking the perilous sea crossing to Europe and many are held in overcrowded detention centres after being intercepted on the high seas
Libya is a favoured departure point for migrants from sub-Saharan Africa risking the perilous sea crossing to Europe and many are held in overcrowded detention centres after being intercepted on the high seas AFP / Mahmud TURKIA

A "security operation" following the escape "was handled professionally and without excessive use of force", a statement added.

Bshara was among hundreds taking part in a sit-in in front of the office of the UN refugee agency (UNHCR) in Tripoli on Saturday.

Dozens of destitute migrants and refugees, including young children, have been sleeping rough in front of the building for days, in the hope of receiving assistance.

African migrants demonstrate outside the Tripoli office of the UN refugee agency demanding repatriation after Friday's shooting deaths again highlighted the appalling conditions they endure in Libya
African migrants demonstrate outside the Tripoli office of the UN refugee agency demanding repatriation after Friday's shooting deaths again highlighted the appalling conditions they endure in Libya AFP / Mahmud TURKIA

"We're extremely tired. But we have nowhere to go, we are even being chased off the pavement," Bshara told AFP tearfully.

"For our security, we ask to be evacuated," one banner at the site said.

"Libya is not a safe country for refugees," read another.

In chaos since its 2011 revolution, Libya has long been a favoured departure point for migrants -- many from sub-Saharan Africa -- fleeing violence and poverty in their own countries and hoping to reach Europe.

IMAGES AND SOUNDBITES Migrants demonstrate outside the headquarters of the United Nations High Commissioner for Refugees (UNHCR) in the Siraj area of the Libyan capital Tripoli, some demanding to leave the country. Guards shot dead six migrants at an over
IMAGES AND SOUNDBITES Migrants demonstrate outside the headquarters of the United Nations High Commissioner for Refugees (UNHCR) in the Siraj area of the Libyan capital Tripoli, some demanding to leave the country. Guards shot dead six migrants at an overcrowded Tripoli detention facility the previous night, according to the International Organization for Migration (IOM), the latest violence against the city's large migrant population. AFPTV / Hosam AHMAD

Hundreds die each year trying to make the dangerous Mediterranean crossing in rickety, overcrowded boats, while NGOs say those waiting to leave are often subject to violence and abuse.

Late last week, Libyan authorities raided multiple houses and makeshift shelters in a poor suburb of Tripoli, in what it said was an anti-drug operation.

The UN said the raids, mostly targeting irregular migrants, left at least one person dead, 15 wounded and saw more than 5,000 detained.

Doctors without Borders (MSF) decried "violent mass arrests".

"There were 39 of us living in the same building" before the raids, Bshara said.

At first, she said she and her family evaded authorities by hiding in a well, but they were eventually found and placed in the Al-Mabani detention centre.

There were so many people there that it was impossible to sleep, said Ismail Derrab, another of those who escaped the facility on Friday.

"We have nothing. We would like to get out of this country," said the young Sudanese man.

Official migrant detention centres in Libya are riddled with corruption and violence, including sexual assault, according to the United Nations and human rights groups.

The UNHCR had said before Friday's shooting deaths that it was "increasingly alarmed about the humanitarian situation for asylum seekers and refugees in Libya".

It temporarily suspended its activities at its Tripoli office this week, citing mounting tensions.

"We renew our appeal to the Libyan authorities to allow the resumption of humanitarian flights out of the country, which have been suspended for almost a year," it said in the earlier statement.

Waffagh Driss, another Sudanese migrant, said that Libyan authorities had targeted migrants "according to the colour of their skin".

"The situation in Tripoli for black people is terrible," the 31-year-old said.

"We are exposed to every kind of danger. Our life is at risk."