TIJUANA, MEXICO -- Attorney General William P. Barr's new multimillion-dollar plan to curb illegal immigration calls for new border lights and fences and 150 additional Border Patrol agents in this area, where nearly half the 1 million arrests along the southern border are made each year.

Javier Ortega, a 40-year-old auto body repairman from Guadalajara, is not impressed.

Ortega and dozens of other men and women -- and a 4-year-old girl -- are standing on the Mexican side of a recently constructed 10-foot-high, solid steel barricade. There is a gaping hole dug under the wall.

"It doesn't matter how many people, horses, bicycles, helicopters or planes they use," Ortega said. "People will go. It doesn't matter if the fence is electric, we'll fry, but we're still going."

If the United States really wants to keep people out, said Carlos, a 28-year-old restaurant worker who did not give his last name, "They need to do it like in {East} Germany and put soldiers every 10 feet and shoot people.

"But even then we'll go," he laughed.

A few hours later -- just after the Border Patrol's afternoon shift change -- a group of eight young men sat atop another section of the wall staring down at a lone agent. The agent turned away for a moment and the group jumped down and dashed about 200 yards toward a K-mart on the U.S. side of the border in San Ysidro, Calif. Other agents gave chase and it appeared some were caught. Others got away.

The nightly ritual had begun. On a rainy night last Wednesday, agents chased as many as 2,000 people -- no one knows for sure -- through the narrow canyons, parking lots, apartment complexes and businesses along the border. Some were picked up by friends or smugglers waiting on the other side. Others walked up Interstate 5.

"We'll always come back," said Luis, a 21-year-old shoe repairman from Mexicali. He said his job last year at a Nebraska meat-packing plant paid eight times what he could earn at home. "We have to look for a way to survive." A Huge Economic Temptation

Immigration and Naturalization Service (INS) officials, civil rights activists and immigration experts interviewed on both sides of the border generally agreed with Luis and his friends: Short of a Berlin Wall solution, with agents instructed to shoot to kill, the huge wage disparity between the United States and Mexico will always tempt large numbers of people to sneak across the border.

They shared Border Patrol agent Ed Conlin's observation shortly after the group dashed to the K-mart. "If someone really, really, really wants to make it, he will. We can't stop him."

They also agree that the number of people trying to cross has increased in recent years, although Hispanic rights groups say INS inflates its estimates, and fails to take into account multiple apprehensions of the same people.

The number of people caught at the border dropped sharply for three years after the 1986 Immigration Reform and Control Act legalized more than 3 million aliens already living in the United States. But apprehensions have increased in the past two years to pre-law levels, with more than 1 million likely to be intercepted this year.

The sharpest disagreement is a longstanding one over whether the barricade and increased agents, sanctions on employers who hire illegal aliens and other enforcement measures can ever succeed in substantially reducing the numbers of illegal entrants.

Barr, announcing the plan Feb. 10 in a speech in San Diego, just north of here, said it was needed to stop illegal aliens from "flouting our sovereignty and ignoring our process." He said he recognized his proposals were not "a silver bullet," but they were a "steady march in the right direction."

Critics of the U.S. enforcement effort say it is a waste of time and resources and may even impede efforts to address the underlying problem -- the 8 to 1 wage gap between the two countries.

U.S. emphasis on police measures, such as the new wall, increases resentment and economic nationalism in Mexico, said Wayne A. Cornelius, director of the Center for U.S.-Mexican Studies at the University of California at San Diego. Barr's proposals "make it more difficult for the Mexican government to adopt free trade policies" needed for a long-term solution.

Focusing on enforcement is "highly inflammatory on the Mexican side, much more than U.S. people realize," he said. "Even if the practical impact {on immigration} is negligible, the symbolic effect is great."

"Every country has a right to control its borders," said Jorge Bustamante, president of the state-funded College of the Northern Frontier in Tijuana, which closely studies immigration.

"But the United States wants to have its cake and eat it too. You want to stop illegal immigration, but you want and need cheap labor," he said. "You cannot have both. It is a U.S. schizophrenia, wanting to open and close your borders at the same time."

As a result, the State Department and economic interests want free trade and a partnership with Mexico, he said, while the INS "treats Mexico as the enemy."

Increased enforcement of the type outlined by Barr "is just a political game," he said. The new steel barricade will do little to stop people, he said, "but it will have a very strong effect on political consumption in Southern California," where anti-immigrant sentiment is strong and growing.

There is some evidence that increased enforcement may in some cases worsen the situation, he said. Higher entry difficulties and costs -- the smugglers dropped their fees after the 1986 law but have raised them back to more than $300 a person -- may be encouraging people to stay longer each time, Bustamante said. The increased stay in the United States then encourages some to bring their families across, actually increasing the magnet effect by the very effort to keep them out.

The 1986 law itself may have created a strong magnet, legalizing millions of male workers who now appear to be bringing over their families in increasing numbers.

But immigration officials insist that, unless the United States is willing to declare the border to be open, the laws must be enforced. James B. Turnage Jr., INS director for the San Diego area, said the 1986 law, which introduced employer sanctions for the first time, can eventually do a great deal to "turn off the {jobs} magnet."

The sanctions, which include fines of up to $3,000 per worker and jail terms for repeated offenses, are "the last best chance short of militarizing the border," he said. "We can certainly control this, and we must.

"This is the most generous country in the world," in terms of number of people legally admitted each year, Turnage said. "It's not closing the golden door, but we can't continue on having people crashing in through the back door." Those trying to do so must be told to "get in line and wait your turn like everyone else."

"If this goes on," he said, "there will be a backlash" against all immigration.

Civil rights groups argue there has been a backlash against sanctions, whose effectiveness has been undermined, if not destroyed, by widespread use of forged documents. The threat of sanctions causes employers to discriminate against Hispanic citizens and legal residents, opponents say, and employers also are calling for repealing sanctions. More enforcement, critics argue, will simply increase opposition.

Much of the criticism against new enforcement efforts is misguided and overstated, INS officials said, focusing on each element, rather than the broader enforcment plan.

No one enforcement tool will deter illegal immigration, Turnage said, adding that there needs to be a "comprehensive approach" including employer sanctions and increased border security.

INS officials say they are under no illusions that the new steel barricade, which will eventually extend inland from the ocean for about 14 miles, will keep people out. "It's not a people fence," said Gustavo De La Vina, head of the Border Patrol here. "It doesn't stop people."

But it has dramatically reduced the ability of large numbers of people and drug smugglers to simply drive pickups and cars across the border. It has reduced rock-throwing at agents in their vehicles, he said, and has made it more difficult for some to get across, especially women and children. Fence Provides 'More Control'

The fence has had a "funneling effect," he said, forcing people to circle around it, which moves them away from business and residential areas into rougher and more open terrain, where they can be caught.

The fence has provided "more control to a situation that had been out of control," he said, and "the more difficult it is, the less they come. It's a deterrent."

But Cornelius said the "Keystone Kops" approach only "forces migrants and smugglers to change tactics," and will simply "cause the revolving door to spin faster."

The barricade itself, critics speculate, may have induced hundreds of men, women and children earlier this month to adopt the dangerous tactic of running en masse through Mexican customs checkpoints and up Interstate 5 against the southbound traffic. The new ploy has been blocked by Mexican authorities who have stopped people from congregating on that side of the border.

Employer sanctions, Cornelius said, have spawned a "cottage industry" of fraudulent documents.

There is "no alternative" but a "developmental approach" under a Mexican-American free trade agreement, he said, so that Mexican wages would become more comparable with U.S. wages. They need not be equalized, he said, but reducing them from 8 to 1 to roughly 4 to 1 would be enough to dramatically reduce the northward flow.

Critics of that approach argue that it will take decades or generations to have any effect, and the problem is growing now.

"Free trade is not a quick fix," Cornelius acknowledged, "but it is not going to take decades. I think you could see some significant improvement in five to 10 years . . . not generations. The current levels of illegal migration are not inevitable. What happens on the Mexican side is what will determine the flow."

Later Wednesday evening, a dozen would-be entrants sat in a Border Patrol van en route to processing and a brief detention. Some of them had been among a group of about 100 who had gathered an hour earlier at the eastern edge of the steel fence, waiting only for agent Conlin's van to move on.

Several were in good spirits, having been caught many times before, and cheerfully vowed to try again the next night. But one woman, about 25 years old, sat forlornly at the front.

"We Mexicans have to suffer so much," she said to a reporter.