Mexico has asked Washington to abandon its plan to dig a ditch near San Diego along a four-mile stretch of border that drug smugglers and illegal immigrants now cross in vehicles.

U.S. officials have said the 8-foot-deep, 14-foot-wide ditch was originally planned to improve drainage along the border on the relatively flat Otay Mesa.But more recently, they said it could also discourage narcotics traffickers and illegal aliens from crossing the border in cars and trucks. On Friday, U.S. Immigration and Naturalization Service Commissioner Alan Nelson said construction could begin within two months and should be completed by summer.

In a statement late Monday, the Foreign Ministry asked the State Department to abandon plans to dig the ditch "and immediately begin a study of other alternatives that would permit a quick and acceptable solution to the problem of floodwaters on the Otay Mesa."

Ministry officials reacted with surprise in late January to news reports that one purpose of the planned ditch would be to deter drug smugglers and illegal immigrants.

They said they had only been told the ditch, about 25 miles southeast of downtown San Diego, was meant to improve drainage.

The project has since been criticized by people on both sides of the border. Some have likened it to the Berlin Wall, and several Mexican legislators called it an "unfriendly" gesture.

Immigration officials say the isolated Otay Mesa is the most popular crossing point for illegal immigrants.