Beirut, Lebanon - Most people passing by the busy Adlieh intersection in east Beirut are probably unaware that several floors underground, hundreds of people languish in a makeshift detention centre. "It's like a tomb," Abbas, a former detainee of the underground facility, told Al Jazeera.
Although it is intended as a temporary holding centre for foreign nationals, some inmates have been held at the facility for weeks, months or even years. Once used as an underground parking lot, before being converted to a prison in 2000, former inmates have reported being held in inhumane conditions, with no natural sunlight, minimal ventilation and frequent overcrowding.
Those kept for extended periods are being held in arbitrary detention, the Lebanese Center for Human Rights (LCHR) said in its 2013 report, "Arbitrary Detention and Torture in Lebanon".
"People are here and they don't know when they will be released or deported," said Wadih al-Asmar, LCHR's secretary-general. "It's a kind of legal kidnapping."
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Under Lebanese law, all foreigners who have served sentences for criminal offences in Lebanon, or are found to be staying in the country without a valid permit, are detained at the facility, which is overseen by General Security, the national security agency which oversees immigration.
General Mounir Akiki, a spokesperson for Lebanon's General Security, told Al Jazeera that detainees should be held for no longer than a week, but that "the detention period can be longer if there are any delays, if embassies or consulates fail to cooperate, or due to the difficulty of ascertaining the nationality of some [detainees]".
Lebanese law does not give guidelines [for this kind of detention], so in the absence there's no time limit on how long they can be held.
But according to Nadim Houry, the deputy director for Human Rights Watch in the Middle East-North Africa region, the problem is the lack of oversight into the length and justification for detention at the facility.
"Lebanese law does not give guidelines [for this kind of detention], so in the absence, there's no time limit on how long they can be held," said Houry.
Many of the detainees are migrant domestic workers who have fled their employers. Stories of abuse of domestic workers abound in Lebanon, where the kafala system ties residency to employment, making it difficult for workers to leave the country.
Other detainees are in the country illegally and simply do not have sufficient funds to pay for a flight to leave. Many have little idea of why they are being held for so long, with minimal access to legal help. They are isolated and lack a support network in Lebanon.
"Part of the problem is that for many of the detained, they don't have anyone to speak to on the outside," Houry said.
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Many of the detainees are also refugees. Lebanon is not a signatory to the United Nations Convention on Refugees, and therefore does not officially recognise refugee status, leaving those who cannot return to their home countries effectively stuck in the centre. The exception, so far, have been Syrian detainees.
Despite an increasing number in Lebanon with expired residency permits - unable or scared to renew them - detained Syrians are generally released within two to three days, said the UN High Commissioner for Refugees.
I lost my feelings, my soul, my mind, my body, my everything... In Adlieh, I am not human.
Abbas, who asked that his name be changed as he feared reprisals from the security services, had already served an extended sentence for a minor, non-violent crime when he was referred to the Adlieh detention centre in 2010. He fled his country and has legal residency in Lebanon. Nonetheless, he was held at the centre for more than three months.
"I lost my feelings, my soul, my mind, my body, my everything," he said of the experience of sharing a dank cell with dozens of other men. "In Adlieh, I am not human."
Abbas said officers put pressure on him to sign deportation papers to return to his home country. After he refused, they held him in the centre. The same year he was detained, human rights group Frontiers Ruwad criticised General Security after it said 14 Iraqis were coerced into signing deportation papers.
At its busiest, scores of detainees share cells of around 40sq metres. Space is so limited you sleep laying "like this", Abbas said, holding his hands tightly together.
Another former detainee told Al Jazeera that the cells are "dank and full of cockroaches", while running water is available for just two brief periods a day. Columns left over from its time as a parking lot delineate the cells, each of which has a toilet and a makeshift shower. Sanitation is minimal.
"The smell is terrible," said Abbas. "Most people were sick because of the conditions." Even Roumieh, the notorious Lebanese prison where he spent several years, was preferable, Abbas said. "In Roumieh you can talk [to people outside the prison], you have the sun, you can talk with [visiting] NGOs."
Abbas was eventually released after intervention from the Lebanese judiciary. But he said his experience at Adlieh has made him fearful of the security services.
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The number of detainees held for long periods at Adlieh has been in decline for the past few years, according to Asmar. This prompted hopes that it would soon close or move to a refurbished location, but the numbers have steadily increased.
It is shameful for us to be here. It is a shame for our soldiers, and for the people who are detained.
General Security officials told Al Jazeera the facility currently holds 310 detainees, under the centre's intended limit of 350. But at a meeting of the parliamentary committee on human rights in June, LCHR was told by a representative from General Security that the centre was holding 550 people. Reports from last year, meanwhile, put the number at over 700.
In response to the increased numbers, LCHR and other groups have renewed their calls for the centre to close. In late June, a demonstration was planned in Beirut to protest the detention centre, but was cancelled and re-scheduled for this week.
"It is shameful for us to be here. It is a shame for our soldiers, and for the people who are detained," Akiki told Al Jazeera.
Rumours have circulated that a new detention centre is being planned, with vastly improved conditions. Last November, the Lebanese Daily Star reported that development of the new centre had stalled because of a lack of funding.
While improved conditions will be welcomed, Asmar said they don't resolve the underlying problems. "The main issue is that they cannot have a detention facility without a legal framework," he said. "Even if it is not underground, they will still have a legal problem detaining people in this way."