A private group proposed elaborate measures Thursday to seal the southern border against illegal immigrants but derided government plans for a car-blocking ditch south of San Diego as "too little too late."

The Federation for American Immigration Reform proposed installing stronger and higher metal fences, concrete barriers and electronic surveillance equipment along the 200 miles of the Mexican border where most illegal immigration occurs."If we are to regain control of the southern border, we will have to begin to deter illegal entry rather than merely apprehend those hundreds of thousands of illegals who cross our northern and southern land borders every year," said the report. "Locking uninvited gate-crashers out is just good common sense."

The report was issued a day after the Border Patrol announced plans to build a 5-foot-deep, 4-mile-long ditch in an attempt to stop drug smugglers from driving across a desert from Mexico to San Diego.

The ditch, which Associate Attorney General Francis A. Keating II likened to a "buried Berlin Wall," will traverse an area east of San Ysidro, Calif., that is a major drug smuggling route.

But Patrick Burns, assistant director of FAIR, said "the drainage ditch is too little too late if it is to be taken seriously as a method of deterring illegal entry."

Burns' group proposed charging a $2 user fee for every person who crosses the border to finance construction of better fences and stepped-up border patrols.

The non-partisan organization's advisory committee includes former Attorney General William French Smith, ex-Sen. Walter D. Huddleston, D-Ky., and former Colo. Gov. Richard Lamm.

The flood of illegal immigrants, reflected by the increase of border arrests from 202,111 in 1970 to 1.9 million three years ago, can't be stopped unless the border is more secure, the group said.

"Everyone has the right to lock his own back door. Those who ignore the lock and enter without permission are guilty of breaking and entering. This is the transgression of the illegal alien," it said.

Burns said the Border Patrol's planned ditch would be an obstacle only to a fraction of illegal immigrants entering southern California. He noted that illegal aliens account for 20 percent of the felony arrests in San Diego County.

San Ysidro, with more than 50 million crossings annually, is the world's busiest port of entry, the report said.

For this region, the report proposes building a 20-mile-long, 12-foot sunken concrete retaining wall topped by an eight-foot metal fence. The earth would be graded so that the concrete wall would be built into the ground.

"Illegal aliens would face nothing less than a smooth vertical wall that would be virtually impossible to scale without a ladder."

The government's proposed ditch was termed a potential deathtrap by one Mexican-American leader.

"If it's an obstacle that could injure someone, then we cannot tolerate it," Jess Haro, president of San Diego's Chicano Federation, said Wednesday. "I'd like to believe that we are not in the business where we are out to maim people."

Similar sunken earth fences are proposed for El Paso, Texas, which accounts for 20 percent of southern-border arrests.

Concrete rails and secure metal fences are proposed for other border areas.

Most of the remaining 1,800 miles of the U.S.-Mexican border is over such treacherous terrain that few people attempt to enter the country there, the report said.