A/HRC/7/4 page 18 to administrative detention. The degree of procedural safeguards varies in terms of the possibilities for review of the legality of detention and its frequency. In practice some States misleadingly label immigration detention centres as “transit centres” or “guest houses” and detention as “retention” in the absence of legislation authorizing deprivation of liberty. 44. The Working Group has witnessed numerous problems surrounding the detention of asylum-seekers and illegal immigrants, which are informed by the existence of different legal frameworks, or a lack thereof, or by practices which are in violation of national immigration legislation or applicable international human rights laws. 45. Mandatory detention of illegal immigrants or even of asylum-seekers, who are not criminals, is an issue of growing concern for the Working Group. A straight analysis of the statistics indicates that in some countries the numbers of non-citizens in administrative detention exceeds the number of sentenced prisoners or detainees, who have or are suspected of having committed a crime. Some States even make it a criminal offence punishable with imprisonment to enter a country illegally. 46. While administrative detention of asylum-seekers and illegal immigrants is not prohibited a priori by international human rights law, it can amount to arbitrary detention if it is not necessary in all circumstances of the case. Moreover, detention during the period when attempts are being made to establish the identities and nationalities of asylum-seekers and illegal immigrants or to secure their deportation cannot usually be considered an effective solution. Expulsion proceedings require the cooperation of the country of origin of the person concerned. The lack of interest or the inability of the country of origin to effectively cooperate with the country of entry often prevent the completion of such proceedings or cause long delays. In some countries the immigration rate has significantly increased, others are simply overwhelmed by a phenomenon new to their Governments, even if the influx of aliens is relatively limited in numbers. Consequently, illegal immigrants and asylum-seekers, including children and trafficked persons, may face a detention term of several months or years or even a (potentially) indefinite one in countries where it is mandatory to keep them in custody, or which otherwise resort to unlimited or indefinite detention provided for by domestic laws. During its country missions the Working Group met with many non-citizens who had been detained for months, some for years. 47. Instances of excessive administrative custody of illegal immigrants may occur even in countries with strong safeguards against arbitrary detention, particularly if the expulsion of an illegal immigrant cannot be carried out for legal, logistical or other reasons; for example, if deportation would violate the principle of non-refoulement, or if means of transportation to the country of origin are simply not available. 48. In its Opinion 45/200611 the Working Group declared arbitrary, inter alia on the grounds of its excessive length, the detention of a Somali citizen liable for removal which could not be 11 Addendum 1 to this report.