2010 around 520 Sahrawi civilians remained "disappeared" by Moroccan forces, according to human rights groups; some estimate that the total number of "disappeared" could be as high as 1,500. In the past, Morocco denied that any such political prisoners existed, but in 1991 released nearly 200 "disappeared" prisoners, many of whom had been held in secret detention centers since the mid-1970s. Since then, there have been no further releases of "disappeared" prisoners. Amnesty International stated in a 1999 report that: . In May 2005, the remains of 43 Sahrawi "disappeared" were exhumed from secret prisons on the south of Morocco (Kalaat Maguna, Tagunit). They were detained in Western Sahara (Laayoune, Smara) & southern Morocco (Tan-Tan, Assa) in the 1970s and 1980s. In 2008, the head of CORCAS and former leader of the Sahrawi National Union Party, Khelli Henna Ould Rachid, declared: "Some Moroccan army officers have made what might be called war crimes against prisoners outside the scope of the war ... Many civilians were launched into space from helicopters or buried alive simply for being Sahrawis". The same year (4 January) construction workers uncovered a mass grave with approximately 15 skeletons in Smara, in former military barracks built during the 1970s, the period during which many Sahrawis disappeared or were murdered by Moroccan authorities. Resulting from the "Reconciliation tribunals" in Morocco in 2005, some graves of political dissidents of Hassan II regime (Sahrawis & Moroccans) were uncovered, although the responsible persons of those crimes have never been judged or their identities revealed. Also, the testimonies of witnesses have not been published yet. In March 2010, a new grave was found by Bou Craa workers on a phosphate mine with 7 corpses, supposedly Sahrawi nomads killed by Moroccan forces during the mid-1970s. Freedom House In late 2005, the international democracy watchdog Freedom House listed the abuses of human rights by Morocco. Those relating to political processes were: controlling elections and not allowing Sahrawis to form political associations (such as labor organizations) or non-governmental organizations. The paper included reports of repressive measures against demonstrators. Amnesty International After repeatedly calling attention to alleged human rights violations in Moroccan-controlled Western Sahara, Amnesty International (AI) received, in April 2006, two detailed responses from the Moroccan Ministry of Justice. The Ministry declared that human rights defenders were not stopped and were not taken into custody because of their opinions, but because of their implication in