As it prepares to mark the International Day of the Disappeared on Thursday, the International Commission on Missing Persons urged governments to provide families with answers about the fates and whereabouts of their missing loved ones. Human rights groups called such disappearances a crime against humanity that must be stopped.

WHO IS A MISSING PERSON?

Individuals reported missing because of in-country or international armed conflicts, or disturbances that require action by a neutral and independent body. Also, people who have been taken into custody by officials who refuse to publicly acknowledge that or conceal the fate and whereabouts of the disappeared persons.

WHICH ARE THE MOST PROMINENT CASES?

ARGENTINA — Some 13,000 people are officially considered missing, thanks to the 1976-83 dictatorship in the military junta's campaign to eliminate political dissenters. Human rights groups say that number is 30,000. People were kidnapped, thrown in the back of trucks and taken to clandestine torture camps. Many were drugged, chained and thrown alive from airplanes into the Rio de la Plata river. A "Never Again" commission formed shortly after Argentina's democracy was restored in 1983 documented thousands of crimes against humanity during the military regime, but hardly any of the violators were prosecuted until Nestor Kirchner was elected president 20 years later.

BOSNIA — Bosnian Serb troops overran the U.N.-protected enclave of Srebrenica in July 1995, killing an estimated 8,000 people. Most of the Bosnian Muslim men and boys were executed and buried in mass graves. Serbs tried to hide the crime by digging up the graves and distributing the remains in several other secret sites. The process led to the bones of the same people being found in several graves, or not found at all. More than 10,000 people, out of the 14,000 people still missing from the 1991-95 wars in the former Yugoslavia, are linked to the Bosnian conflict.

CAMBODIA — In 1975-1979, Cambodia's brutal Khmer Rouge orchestrated a genocidal reign of terror ostensibly aimed at creating an agrarian utopia. By the time it was over, an estimated 1.7 million people were dead from executions, starvation and overwork. That number includes many missing people. Although several hundred mass grave sites have been found, most were never dug up. There has never been any comprehensive research or study to determine the number of missing. Countless families in Cambodia today have missing relatives who were never found and are presumed dead. A U.N.-backed tribunal was set up in 2006, but after six years and $160 million it has just begun the trials of three top Khmer Rouge leaders and only convicted former prison chief, Comrade Duch.

IRAQ — An estimated 15,000 people have been missing in Iraq since the U.S.-led war, which began in 2003 and ended last year. Kamil Amin, a spokesman for Iraq's human rights ministry, said it has created a database of the missing, based on their relatives' accounts of their names, addresses, when they were last seen and the kind of clothes they were wearing when they disappeared. However, the ministry did not ask for international assistance in locating the people "because we consider the cases of those missing people as isolated and criminal cases."

KOREAS — North Korea abducted about 86,000 South Koreans during the 1950-1953 Korean War and 700 others after it, according to the Seoul-based, government-affiliated National Committee on Investigating Abductions during the Korean War. South Korea has asked North Korea to return the abductees, but the North denies kidnapping them, according to committee official Kim Suk-nam.

TURKEY — Although many mass graves in Turkey can be traced to the beginning of the century, a map recently published in the daily Radikal highlights the startling extent of such sites dating from the 1990s, when the war between the Turkish state and the Kurdish nationalist Kurdish Workers' Party was at its prime. The bodies of thousands of people were unceremoniously dumped into mass graves, says Amnesty International.

PAKISTAN — Pakistan has joined a list of countries practicing enforced disappearance. People who have disappeared include foreign and Pakistani nationals suspected of links to terrorist groups and political opponents of the Pakistani government pushing for greater rights for their communities, including Baloch and Sindhis.

SRI LANKA — Its civil war ended in 2009 after government troops defeated Tamil Tiger rebels who were fighting for a separate state in the country's north and east. Since then both government forces and rebels have been accused of rights violations during the conflict. The government has maintained a heavy military presence in the north, despite international calls for a reduction of troops there. Scores of ethnic Tamils suspected of having links with the rebels have disappeared, and so have several dissidents.

OTHER COUNTRIES OR REGIONS WITH MANY MISSING PERSONS

Armenia, Azerbaijan, Brazil, Burundi, Chile, Colombia, Croatia, East Timor, Eritrea, Ethiopia, Georgia, Guatemala, Israel, Iran, Ivory Coast, Jordan, Kuwait, Kyrgyzstan, Lebanon, Libya, Mexico, Nepal, Peru, Russia, Senegal, Serbia, Kosovo, Uganda, Western Sahara

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