The government is planning to dig a 4-mile-long ditch along the U.S.-Mexican border near San Diego to reduce "the deluge" of illegal drugs being smuggled in, a Justice Department official said Wednesday.

Associate Attorney General Francis A. Keating II said the ditch, which he likened to a "buried Berlin Wall," will be dug along a stretch of flat desert east of San Ysidro, Calif.Its main purpose will be to discourage drug smugglers from driving trucks and cars across the border between two points of entry rather than to snare illegal immigrants.

"I can say it will be applauded by people who are sick and tired of the deluge of cocaine and heroin that is flowing across the Mexican border," Keating said.

The permanent ditch, which will probably be lined with concrete, will be wide and deep enough to discourage cars and trucks from driving across it, Keating said.

He said he proposed the idea to the Immigration and Naturalization Service and the plan was approved last month by Attorney General Dick Thornburgh.

"No country is a country that cannot protect its border; this is one of many systems to do it," Keating said.

Keating said the government had no plans to dig similar ditches along other stretches of the U.S.-Mexican border, saying officials would first want to determine if the California trench was successful.