TUCSON  The unforgiving terrain of the Sonoran Desert, south of here, whose searing summers and frigid winters claim hundreds of lives each year, has long been a favored avenue of entry for illegal immigrants from Mexico and other Latin American countries. But in the last year, the authorities say, smugglers have increasingly capitalized on a much more lucrative business  trafficking Chinese citizens into the United States.

The number of Chinese immigrants arrested while illegally crossing the border into Arizona through the busiest smuggling corridor in the United States increased tenfold in the last fiscal year, according to the United States Border Patrol in Tucson.

In fiscal 2009, 332 Chinese immigrants were caught in the Border Patrol’s Tucson sector, up from 30 the previous year, Border Patrol figures showed. And in what could be a sign of a record-breaking pace for this year, agents in the Border Patrol’s Tucson sector arrested 281 Chinese immigrants from Oct. 1 to Dec. 31, the first quarter of the current fiscal year.

The reason is simple: dollars and cents.

As record quantities of illegal drugs are being intercepted in Arizona, those involved in taking people and drugs across the border are increasingly concentrating on the more rewarding smuggling of Chinese immigrants, said David Jimarez, a spokesman for the Border Patrol.