The number of illegal aliens apprehended on the southern U.S. border has reached a six-year low, but the numbers of non-Mexican aliens arrested increased over fiscal 1987, immigration officials said Friday. ``The decline in apprehensions confirms the downward trend that began immediately after passage of the Immigration Reform and Control Act and shows that the law is working as it was intended,'' said Alan C. Nelson, commissioner of the Immigration and Naturalization Service. Apprehensions totaled more than 940,000 in the fiscal year ending Oct. 1, while there were 1.12 million apprehensions in fiscal 1987 and a record 1.62 million in 1986. At a news conference, Nelson acknowledged that temporary reassignment of some border control agents during the fiscal year may account for some of the decline. He said other factors are the decreased number of illegal aliens in the United States because of mass legalizations under the 1986 immigration act and the fact that drought conditions contributed to less demand for farm laborers. The number of non-Mexican immigrants apprehended increased last fiscal year to 39,000 from 37,000 in 1987, other officials said, with about a fourth of those each year from El Salvador and the rest from more than 100 other countries. Nelson said the fact that the trend has not been the same for non-Mexicans is probably ``a function of distance.'' He said people who have to travel greater distances from other countries to the border are more likely not to be deterred by aggressive enforcement or changes in immigration laws. Nelson said the INS increased its Border Patrol forces to record numbers during the year, with plans to have 1,400 new agents on duty by next June, bringing the total along the southern border to 4,300. Investigation staff has increased 75 percent since last fiscal year, he said. This has resulted in apprehension of 50,000 criminal aliens, up from 33,500 a year earlier, Nelson said. ``These figures show we are making more effective use of our enforcement resources by concentrating them on the most serious problems of illegal immigration _ that is, we go after the aliens who are causing the most harm to society,'' he said. Border Patrol seizures of narcotics along the southern border increased from 2,751 cases to more than 3,000 last year, increasing in value by $100 million to $681.1 million for the fiscal year, Nelson said. He said the INS has received 2.65 million applications for temporary resident status under the immigration law, including nearly twice as many as expected under the less restrictive program for special agricultural workers _ more than 890,000. Nelson said 97.5 percent of regular applications and 92 percent of those under the agricultural program are approved. Farm-worker applicants have to show only that they worked on a U.S. farm for 90 days during the previous year to get legal status. Officials say there are some cases of obvious fraud in the program, including applicants who obviously are too well manicured to be farm workers and some who claim such things as having picked strawberries from trees. Of pending cases, 168,000 are suspected to be fraudulent applicants, including 136,000 for the agricultural program, said Nelson. He said fewer than 51,000 applications have been denied under the immigration act, with 2,844 involving fraud.