MEXICO CITY - Mexico's immigration chief says there has been a sharp drop in the number of Central Americans crossing Mexico to reach the U.S.

Commissioner Salvador Beltran del Rio says the number of Central Americans crossing Mexico without documents has dropped from 433,000 in 2005 to 140,000 in 2010. He says the downward trend has continued in the first eight months of this year.

Beltran said in a videoconference Monday that Central Americans crossing Mexico face increased risks of extortion, kidnapping and violence because organized crime has moved into migrant trafficking.

In one of the worst attacks, 72 migrants were slaughtered in the border state of Tamaulipas in August 2010. Most were Central Americans.