LOS ANGELES, March 8 (Xinhua) -- As fewer illegal immigrants cross the U.S.-Mexico border, arrests in the last five months are down 24 percent from the same period last year, a newspaper report said on Sunday.

    Authorities attributed the drop to the worsening economic situation and strengthened security at the border, the Los Angeles Times said.

    The sharp drop in arrests of illegal immigrants was unseen since the 1970s as the ailing U.S. economy and enhanced enforcement appear to be deterring people from trekking north, the paper said.

    From October 2008 through February of this year, the Border Patrol arrested 195,399 illegal immigrants, a 24-percent decrease from the same period last year, the paper cited Border Patrol statistics.

    The apprehension level is on track to dip to about 550,000 for this federal fiscal year, the lowest level since 1975, when 596,796 immigrants were caught, statistics showed.

    The downward trend in arrests -- considered one of the best indicators of illegal immigrant migration -- began a few years ago, about the same time the federal government started fortifying the border with more agents, fencing and infrastructure, said the paper.

    But the border enhancements weren't enough on their own to stop immigrants from entering the country, the paper noted, adding that with the U.S. economy in a tailspin, few incentives remain for immigrants to endure the increasingly difficult crossings.

    "A lot of people who would have come here illegally and stayed illegally are not bothering to come to the U.S.," Demetrios Papademetriou, president of the Migration Policy Institute, a Washington-based think tank, was quoted as saying. "The information that they are getting basically says there are no opportunities here."

    The current downward trend breaks with past immigration patterns, when federal crackdowns in one place only led immigration flows to shift to other areas, according to the paper.