Gov. Arnold Schwarzenegger on Sunday said that building a 700-mile wall along the Mexican border to deter illegal immigration would amount to "going back to the Stone Ages," and instead urged the use of high-tech gear and more patrols to secure the nation's southern boundary.

"We are landing men on the moon and in outer space using all these great things. I think that other technology really can secure the borders," the Republican governor said in an interview on ABC's "This Week."

"If I say now, 'Yes, let's build the wall,' what would prevent you from building a tunnel? I mean, we've detected tunnels left and right that people can drive trucks through," he added.

The comments were Schwarzenegger's most detailed to date on the wall proposal, which was included in legislation enacted in the U.S. House of Representatives. Schwarzenegger has said previously that fences might be appropriate in some areas, but raised doubts about the effectiveness of a wall snaking along the border.

Speaking on ABC, the governor said, "I think that it will be ludicrous to limit yourself to just building a wall. We're going back to the Stone Ages here."

But he also suggested practical and symbolic reasons to oppose the proposal. He alluded to the Berlin Wall, suggesting that such a structure on the U.S. border would send the wrong message to Mexico, "our friends ... our trading partners."

Schwarzenegger, a native of Austria, also repeated his opposition to amnesty for illegal immigrants, but provided few specifics of what requirements an illegal immigrant should have to meet to achieve legal status.

He also said it's unrealistic to consider uprooting or driving out the nation's estimated 11 million illegal immigrants.

"It would cost $500 billion. Who's going to pay for that?" he asked.

Schwarzenegger immigrated to the U.S. in 1968 and became a naturalized citizen in 1984, but has retained his Austrian citizenship.