E/CN.4/2004/76/Add.2 page 19 Spain this represents a disproportionate obligation, given the constant and growing transit of persons over this southern frontier of Europe. 77. The Special Rapporteur noted that in practice the investment in resources and technology, the introduction of legislative changes and the implementation of policies aimed at curbing illegal immigration have not been sufficient to bring about a decrease in the phenomenon. She observed how migrants end up trying to enter Spain by other far more dangerous means in the hands of the networks, in many cases paying for it with their lives. She was also able to appreciate the work of the State security forces and bodies in saving lives and providing emergency assistance to migrants. 78. The Special Rapporteur considers that the difficulties involved in curbing illegal immigration are due to many factors, including the difficult economic and political situation of the countries of origin and the view that the migrants have of Spain and Europe as a paradise of opportunities. Some migrants are deceived by the trafficking networks, but others are encouraged to try their luck by relatives and friends already living and working legally or illegally in Spain or elsewhere in Europe. The Special Rapporteur noted that there is a considerable need for migrant workers in some sectors of the Spanish economy, such as the agricultural sector and domestic labour, and that many illegal migrants end up being exploited in the black economy. 79. The Special Rapporteur considers that the strengthening of control systems should be proportionate to solutions comprising family reunification and integration of migrants who have already been in Spain for several years. 80. The Special Rapporteur is concerned about the presence of a growing number of illegal migrants in Spain due to the difficulty of curbing the influx of such migrants and carrying out expulsions. As a result of the various changes in the legislation on immigration and the steady increase in the number of cases, immigration offices have been overwhelmed, with subsequent delays in procedures and ensuing illegality for many migrants. 81. The Special Rapporteur noted a lack of knowledge of the guarantees and rights which the law accords and recognizes for migrants. This situation may result in cases of arbitrary decisions and possible violations of human rights. Particularly in the contexts of interception, return, expulsion and detention, migrants run the risk of defencelessness in the face of possible abuses and violations owing to the absence or insufficiency of legal assistance. 82. The Special Rapporteur noted that there is considerable tension between the Government and some NGOs, not only with regard to immigration policies, which the NGOs often criticize, but also over the enforcement of the Aliens Act. She considers that the work NGOs are doing to assist and protect the rights of migrants is of fundamental importance. She nevertheless noted that in some cases, in a number of NGOs and in the press, there is a tendency to equate the situation of illegal migrants with that of refugees. In addition, in some sectors of the Government and the press, there is a tendency to accuse NGOs of adopting this position. The Special Rapporteur considers that this confrontation may be prejudicial to the protection of the rights of migrants and asylum-seekers, and believes that the proper enforcement of the law is the only way of ensuring respect for the rights of both groups.